[PATCH v2 00/10] Data in direntry (dirdata) feature

[PATCH v2 00/10] Data in direntry (dirdata) feature

[Artem Blagodarenko]

EXT4 currently stores a hash in the directory entry
(dirent) immediately after the file name to support
simultaneous fscrypt and casefold functionality.

It has been discussed within the EXT4 community that
this hash could instead be stored in dirdata. This
would make it the second (or third, in the case of
64-bit inode counts) user of dirdata.

At the same time, the existing format—where the hash
is placed after the file name—must continue to be
supported. With these patches, EXT4 can handle the
hash in both formats.

The first user of this feature is  LUFID -
Locally Unique File ID.

Support for fscrypt and case-insensitive directories
with dirdata enabled has been verified using a
dedicated xfstest submitted to the xfstests list as
a separate patch.

e2fsprogs support is provided in a separate patches
series.

Changes in v2:
- Split the patch set into 10 smaller patchesfor
  easier reading and review.
- Added an IOCTL to set the LUFID for testing purposes.
  LUFIDs can be listed via debugfs. Corresponding support
  has been added in the related e2fsprogs series.
- Removed the dirdata mount option.
- Fixed the following issue:
  KASAN: slab-out-of-bounds read in __ext4_check_dir_entry
- Rebased onto the latest codebase.

Artem Blagodarenko (10):
  ext4: replace ext4_dir_entry with ext4_dir_entry_2
  ext4: add ext4_dir_entry_is_tail()
  ext4: refactor dx_root to support variable dirent sizes
  ext4: add dirdata format definitions and access helpers
  ext4: preserve dirdata bits in get_dtype()
  ext4: add ext4_dir_entry_len() and harden dirdata parsing
  ext4: rename ext4_dir_rec_len() and clarify dirdata usage
  ext4: dirdata feature
  ext4: add dirdata set/get helpers
  ext4: Add EXT4_IOC_SET_LUFID ioctl for setting LUFID on directory
    entries

 foofile.txt               |   0
 fs/ext4/dir.c             |   9 +-
 fs/ext4/ext4.h            | 205 ++++++++++++-
 fs/ext4/inline.c          |  37 ++-
 fs/ext4/ioctl.c           |  62 ++++
 fs/ext4/namei.c           | 587 +++++++++++++++++++++++++++-----------
 fs/ext4/sysfs.c           |   2 +
 include/uapi/linux/ext4.h |  13 +
 8 files changed, 723 insertions(+), 192 deletions(-)
 create mode 100644 foofile.txt

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Tested-by: syzbot@syzkaller.appspotmail.com
-- 
2.43.7

[PATCH v2 01/10] ext4: replace ext4_dir_entry with ext4_dir_entry_2

[Artem Blagodarenko]

From: Artem Blagodarenko <artem.blagodarenko@gmail.com>

Replace remaining uses of struct ext4_dir_entry in namei.c
with struct ext4_dir_entry_2.

The code paths affected by this change already depend on the
filetype feature, so using struct ext4_dir_entry_2 is
appropriate and avoids mixing the two directory entry types
unnecessarily.

This change does not affect support for 16-bit rec_len.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 fs/ext4/namei.c | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 4a47fbd8dd30..5805001ff1d9 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -102,7 +102,7 @@ static struct buffer_head *ext4_append(handle_t *handle,
 }
 
 static int ext4_dx_csum_verify(struct inode *inode,
-			       struct ext4_dir_entry *dirent);
+			       struct ext4_dir_entry_2 *dirent);
 
 /*
  * Hints to ext4_read_dirblock regarding whether we expect a directory
@@ -128,7 +128,7 @@ static struct buffer_head *__ext4_read_dirblock(struct inode *inode,
 						unsigned int line)
 {
 	struct buffer_head *bh;
-	struct ext4_dir_entry *dirent;
+	struct ext4_dir_entry_2 *dirent;
 	int is_dx_block = 0;
 
 	if (block >= inode->i_size >> inode->i_blkbits) {
@@ -160,7 +160,7 @@ static struct buffer_head *__ext4_read_dirblock(struct inode *inode,
 	}
 	if (!bh)
 		return NULL;
-	dirent = (struct ext4_dir_entry *) bh->b_data;
+	dirent = (struct ext4_dir_entry_2 *) bh->b_data;
 	/* Determine whether or not we have an index block */
 	if (is_dx(inode)) {
 		if (block == 0)
@@ -317,13 +317,13 @@ static struct ext4_dir_entry_tail *get_dirent_tail(struct inode *inode,
 	int blocksize = EXT4_BLOCK_SIZE(inode->i_sb);
 
 #ifdef PARANOID
-	struct ext4_dir_entry *d, *top;
+	struct ext4_dir_entry_2 *d, *top;
 
-	d = (struct ext4_dir_entry *)bh->b_data;
-	top = (struct ext4_dir_entry *)(bh->b_data +
+	d = (struct ext4_dir_entry_2 *)bh->b_data;
+	top = (struct ext4_dir_entry_2 *)(bh->b_data +
 		(blocksize - sizeof(struct ext4_dir_entry_tail)));
 	while (d < top && ext4_rec_len_from_disk(d->rec_len, blocksize))
-		d = (struct ext4_dir_entry *)(((void *)d) +
+		d = (struct ext4_dir_entry_2 *)(((void *)d) +
 		    ext4_rec_len_from_disk(d->rec_len, blocksize));
 
 	if (d != top)
@@ -410,22 +410,22 @@ int ext4_handle_dirty_dirblock(handle_t *handle,
 }
 
 static struct dx_countlimit *get_dx_countlimit(struct inode *inode,
-					       struct ext4_dir_entry *dirent,
+					       struct ext4_dir_entry_2 *dirent,
 					       int *offset)
 {
-	struct ext4_dir_entry *dp;
+	struct ext4_dir_entry_2 *de;
 	struct dx_root_info *root;
 	int count_offset;
 	int blocksize = EXT4_BLOCK_SIZE(inode->i_sb);
 	unsigned int rlen = ext4_rec_len_from_disk(dirent->rec_len, blocksize);
 
 	if (rlen == blocksize)
-		count_offset = 8;
+		count_offset = sizeof(struct dx_node);
 	else if (rlen == 12) {
-		dp = (struct ext4_dir_entry *)(((void *)dirent) + 12);
-		if (ext4_rec_len_from_disk(dp->rec_len, blocksize) != blocksize - 12)
+		de = (struct ext4_dir_entry_2 *)(((void *)dirent) + 12);
+		if (ext4_rec_len_from_disk(de->rec_len, blocksize) != blocksize - 12)
 			return NULL;
-		root = (struct dx_root_info *)(((void *)dp + 12));
+		root = (struct dx_root_info *)(((void *)de + 12));
 		if (root->reserved_zero ||
 		    root->info_length != sizeof(struct dx_root_info))
 			return NULL;
@@ -438,7 +438,7 @@ static struct dx_countlimit *get_dx_countlimit(struct inode *inode,
 	return (struct dx_countlimit *)(((void *)dirent) + count_offset);
 }
 
-static __le32 ext4_dx_csum(struct inode *inode, struct ext4_dir_entry *dirent,
+static __le32 ext4_dx_csum(struct inode *inode, struct ext4_dir_entry_2 *dirent,
 			   int count_offset, int count, struct dx_tail *t)
 {
 	struct ext4_inode_info *ei = EXT4_I(inode);
@@ -456,7 +456,7 @@ static __le32 ext4_dx_csum(struct inode *inode, struct ext4_dir_entry *dirent,
 }
 
 static int ext4_dx_csum_verify(struct inode *inode,
-			       struct ext4_dir_entry *dirent)
+			       struct ext4_dir_entry_2 *dirent)
 {
 	struct dx_countlimit *c;
 	struct dx_tail *t;
@@ -485,7 +485,7 @@ static int ext4_dx_csum_verify(struct inode *inode,
 	return 1;
 }
 
-static void ext4_dx_csum_set(struct inode *inode, struct ext4_dir_entry *dirent)
+static void ext4_dx_csum_set(struct inode *inode, struct ext4_dir_entry_2 *dirent)
 {
 	struct dx_countlimit *c;
 	struct dx_tail *t;
@@ -515,7 +515,7 @@ static inline int ext4_handle_dirty_dx_node(handle_t *handle,
 					    struct inode *inode,
 					    struct buffer_head *bh)
 {
-	ext4_dx_csum_set(inode, (struct ext4_dir_entry *)bh->b_data);
+	ext4_dx_csum_set(inode, (struct ext4_dir_entry_2 *)bh->b_data);
 	return ext4_handle_dirty_metadata(handle, inode, bh);
 }
 
@@ -1488,7 +1488,7 @@ int ext4_search_dir(struct buffer_head *bh, char *search_buf, int buf_size,
 }
 
 static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block,
-			       struct ext4_dir_entry *de)
+			       struct ext4_dir_entry_2 *de)
 {
 	struct super_block *sb = dir->i_sb;
 
@@ -1619,7 +1619,7 @@ static struct buffer_head *__ext4_find_entry(struct inode *dir,
 		}
 		if (!buffer_verified(bh) &&
 		    !is_dx_internal_node(dir, block,
-					 (struct ext4_dir_entry *)bh->b_data) &&
+					 (struct ext4_dir_entry_2 *)bh->b_data) &&
 		    !ext4_dirblock_csum_verify(dir, bh)) {
 			EXT4_ERROR_INODE_ERR(dir, EFSBADCRC,
 					     "checksumming directory "
-- 
2.43.7

[PATCH v2 02/10] ext4: add ext4_dir_entry_is_tail()

[Artem Blagodarenko]

From: Artem Blagodarenko <artem.blagodarenko@gmail.com>

Replace open-coded checks for directory tail entries with a call
to ext4_dir_entry_is_tail(). This helper will also be used by
upcoming changes.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 fs/ext4/ext4.h  | 16 ++++++++++++++++
 fs/ext4/namei.c |  7 +------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 94283a991e5c..01b1222b1454 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3917,6 +3917,22 @@ static inline void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
 		io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
 }
 
+/*
+ * ext4_dir_entry_is_tail() - Check if a directory entry is a tail entry.
+ * @de: directory entry to check
+ *
+ * Returns true if @de is a directory block tail entry (checksum record).
+ */
+static inline bool ext4_dir_entry_is_tail(struct ext4_dir_entry_2 *de)
+{
+	struct ext4_dir_entry_tail *t = (struct ext4_dir_entry_tail *)de;
+
+	return !t->det_reserved_zero1 &&
+	       le16_to_cpu(t->det_rec_len) == sizeof(*t) &&
+	       !t->det_reserved_zero2 &&
+	       t->det_reserved_ft == EXT4_FT_DIR_CSUM;
+}
+
 extern const struct iomap_ops ext4_iomap_ops;
 extern const struct iomap_ops ext4_iomap_report_ops;
 
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 5805001ff1d9..0196d954cba1 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -314,7 +314,6 @@ static struct ext4_dir_entry_tail *get_dirent_tail(struct inode *inode,
 						   struct buffer_head *bh)
 {
 	struct ext4_dir_entry_tail *t;
-	int blocksize = EXT4_BLOCK_SIZE(inode->i_sb);
 
 #ifdef PARANOID
 	struct ext4_dir_entry_2 *d, *top;
@@ -334,11 +333,7 @@ static struct ext4_dir_entry_tail *get_dirent_tail(struct inode *inode,
 	t = EXT4_DIRENT_TAIL(bh->b_data, EXT4_BLOCK_SIZE(inode->i_sb));
 #endif
 
-	if (t->det_reserved_zero1 ||
-	    (ext4_rec_len_from_disk(t->det_rec_len, blocksize) !=
-	     sizeof(struct ext4_dir_entry_tail)) ||
-	    t->det_reserved_zero2 ||
-	    t->det_reserved_ft != EXT4_FT_DIR_CSUM)
+	if (!ext4_dir_entry_is_tail((struct ext4_dir_entry_2 *)t))
 		return NULL;
 
 	return t;
-- 
2.43.7

[PATCH v2 03/10] ext4: refactor dx_root to support variable dirent sizes

[Artem Blagodarenko]

From: Artem Blagodarenko <artem.blagodarenko@gmail.com>

Split monolithic definition of dx_root struct to separate dx_root_info
from fake struct ext4_dir_entry2 for improved code readability.
This allows "." and ".." dirents to have different sizes if necessary,
since we can't assume the rec_len 12 if dx_root dirents have dirdata.
Adds dx_get_dx_info() accessor instead of complex typecast at callers.
Does not change any functionality.

Signed-off-by: Pravin Shelar <pravin.shelar@sun.com>
Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 fs/ext4/namei.c | 145 +++++++++++++++++++++++-------------------------
 1 file changed, 70 insertions(+), 75 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 0196d954cba1..87d8cd2c6377 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -244,22 +244,13 @@ struct dx_entry
  * hash version mod 4 should never be 0.  Sincerely, the paranoia department.
  */
 
-struct dx_root
+struct dx_root_info
 {
-	struct fake_dirent dot;
-	char dot_name[4];
-	struct fake_dirent dotdot;
-	char dotdot_name[4];
-	struct dx_root_info
-	{
-		__le32 reserved_zero;
-		u8 hash_version;
-		u8 info_length; /* 8 */
-		u8 indirect_levels;
-		u8 unused_flags;
-	}
-	info;
-	struct dx_entry	entries[];
+	__le32 reserved_zero;
+	u8 hash_version;
+	u8 info_length; /* 8 */
+	u8 indirect_levels;
+	u8 unused_flags;
 };
 
 struct dx_node
@@ -528,6 +519,16 @@ ext4_next_entry(struct ext4_dir_entry_2 *p, unsigned long blocksize)
  * Future: use high four bits of block for coalesce-on-delete flags
  * Mask them off for now.
  */
+static struct dx_root_info *dx_get_dx_info(void *de_buf)
+{
+	/* get dotdot first */
+	de_buf = de_buf + ext4_dir_rec_len(1, NULL);
+
+	/* dx root info is after dotdot entry */
+	de_buf = de_buf + ext4_dir_rec_len(2, NULL);
+
+	return (struct dx_root_info *)de_buf;
+}
 
 static inline ext4_lblk_t dx_get_block(struct dx_entry *entry)
 {
@@ -775,7 +776,7 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
 {
 	unsigned count, indirect, level, i;
 	struct dx_entry *at, *entries, *p, *q, *m;
-	struct dx_root *root;
+	struct dx_root_info *info;
 	struct dx_frame *frame = frame_in;
 	struct dx_frame *ret_err = ERR_PTR(ERR_BAD_DX_DIR);
 	u32 hash;
@@ -787,23 +788,24 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
 	if (IS_ERR(frame->bh))
 		return (struct dx_frame *) frame->bh;
 
-	root = (struct dx_root *) frame->bh->b_data;
-	if (root->info.hash_version != DX_HASH_TEA &&
-	    root->info.hash_version != DX_HASH_HALF_MD4 &&
-	    root->info.hash_version != DX_HASH_LEGACY &&
-	    root->info.hash_version != DX_HASH_SIPHASH) {
-		ext4_warning_inode(dir, "Unrecognised inode hash code %u",
-				   root->info.hash_version);
+	info = dx_get_dx_info((struct ext4_dir_entry_2 *)frame->bh->b_data);
+	if (info->hash_version != DX_HASH_TEA &&
+	    info->hash_version != DX_HASH_HALF_MD4 &&
+	    info->hash_version != DX_HASH_LEGACY &&
+	    info->hash_version != DX_HASH_SIPHASH) {
+		ext4_warning(dir->i_sb,
+			"Unrecognised inode hash code %d for directory #%llu",
+			info->hash_version, dir->i_ino);
 		goto fail;
 	}
 	if (ext4_hash_in_dirent(dir)) {
-		if (root->info.hash_version != DX_HASH_SIPHASH) {
+		if (info->hash_version != DX_HASH_SIPHASH) {
 			ext4_warning_inode(dir,
 				"Hash in dirent, but hash is not SIPHASH");
 			goto fail;
 		}
 	} else {
-		if (root->info.hash_version == DX_HASH_SIPHASH) {
+		if (info->hash_version == DX_HASH_SIPHASH) {
 			ext4_warning_inode(dir,
 				"Hash code is SIPHASH, but hash not in dirent");
 			goto fail;
@@ -811,7 +813,7 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
 	}
 	if (fname)
 		hinfo = &fname->hinfo;
-	hinfo->hash_version = root->info.hash_version;
+	hinfo->hash_version = info->hash_version;
 	if (hinfo->hash_version <= DX_HASH_TEA)
 		hinfo->hash_version += EXT4_SB(dir->i_sb)->s_hash_unsigned;
 	hinfo->seed = EXT4_SB(dir->i_sb)->s_hash_seed;
@@ -827,13 +829,13 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
 	}
 	hash = hinfo->hash;
 
-	if (root->info.unused_flags & 1) {
+	if (info->unused_flags & 1) {
 		ext4_warning_inode(dir, "Unimplemented hash flags: %#06x",
-				   root->info.unused_flags);
+				   info->unused_flags);
 		goto fail;
 	}
 
-	indirect = root->info.indirect_levels;
+	indirect = info->indirect_levels;
 	if (indirect >= ext4_dir_htree_level(dir->i_sb)) {
 		ext4_warning(dir->i_sb,
 			     "Directory (ino: %llu) htree depth %#06x exceed"
@@ -846,14 +848,12 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
 		goto fail;
 	}
 
-	entries = (struct dx_entry *)(((char *)&root->info) +
-				      root->info.info_length);
+	entries = (struct dx_entry *)(((char *)info) + info->info_length);
 
-	if (dx_get_limit(entries) != dx_root_limit(dir,
-						   root->info.info_length)) {
+	if (dx_get_limit(entries) != dx_root_limit(dir, info->info_length)) {
 		ext4_warning_inode(dir, "dx entry: limit %u != root limit %u",
 				   dx_get_limit(entries),
-				   dx_root_limit(dir, root->info.info_length));
+				   dx_root_limit(dir, info->info_length));
 		goto fail;
 	}
 
@@ -939,7 +939,7 @@ static void dx_release(struct dx_frame *frames)
 	if (frames[0].bh == NULL)
 		return;
 
-	info = &((struct dx_root *)frames[0].bh->b_data)->info;
+	info = dx_get_dx_info((struct ext4_dir_entry_2 *)frames[0].bh->b_data);
 	/* save local copy, "info" may be freed after brelse() */
 	indirect_levels = info->indirect_levels;
 	for (i = 0; i <= indirect_levels; i++) {
@@ -2151,44 +2151,38 @@ static int add_dirent_to_buf(handle_t *handle, struct ext4_filename *fname,
 	return err ? err : err2;
 }
 
-static bool ext4_check_dx_root(struct inode *dir, struct dx_root *root)
+static bool ext4_check_dx_root(struct inode *dir,
+			       struct ext4_dir_entry_2 *dot_de,
+			       struct ext4_dir_entry_2 *dotdot_de,
+			       struct ext4_dir_entry_2 **entry)
 {
-	struct fake_dirent *fde;
 	const char *error_msg;
-	unsigned int rlen;
 	unsigned int blocksize = dir->i_sb->s_blocksize;
-	char *blockend = (char *)root + dir->i_sb->s_blocksize;
+	struct ext4_dir_entry_2 *de = NULL;
 
-	fde = &root->dot;
-	if (unlikely(fde->name_len != 1)) {
+	if (unlikely(dot_de->name_len != 1)) {
 		error_msg = "invalid name_len for '.'";
 		goto corrupted;
 	}
-	if (unlikely(strncmp(root->dot_name, ".", fde->name_len))) {
+	if (unlikely(strncmp(dot_de->name, ".", dot_de->name_len))) {
 		error_msg = "invalid name for '.'";
 		goto corrupted;
 	}
-	rlen = ext4_rec_len_from_disk(fde->rec_len, blocksize);
-	if (unlikely((char *)fde + rlen >= blockend)) {
-		error_msg = "invalid rec_len for '.'";
-		goto corrupted;
-	}
 
-	fde = &root->dotdot;
-	if (unlikely(fde->name_len != 2)) {
+	if (unlikely(dotdot_de->name_len != 2)) {
 		error_msg = "invalid name_len for '..'";
 		goto corrupted;
 	}
-	if (unlikely(strncmp(root->dotdot_name, "..", fde->name_len))) {
+	if (unlikely(strncmp(dotdot_de->name, "..", dotdot_de->name_len))) {
 		error_msg = "invalid name for '..'";
 		goto corrupted;
 	}
-	rlen = ext4_rec_len_from_disk(fde->rec_len, blocksize);
-	if (unlikely((char *)fde + rlen >= blockend)) {
+	de = ext4_next_entry(dotdot_de, blocksize);
+	if ((char *)de >= (((char *)dot_de) + blocksize)) {
 		error_msg = "invalid rec_len for '..'";
 		goto corrupted;
 	}
-
+	*entry = de;
 	return true;
 
 corrupted:
@@ -2206,16 +2200,15 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 			    struct inode *inode, struct buffer_head *bh)
 {
 	struct buffer_head *bh2;
-	struct dx_root	*root;
 	struct dx_frame	frames[EXT4_HTREE_LEVEL], *frame;
 	struct dx_entry *entries;
-	struct ext4_dir_entry_2	*de, *de2;
+	struct ext4_dir_entry_2	*de, *de2, *dot_de, *dotdot_de;
 	char		*data2, *top;
 	unsigned	len;
 	int		retval;
 	unsigned	blocksize;
 	ext4_lblk_t  block;
-	struct fake_dirent *fde;
+	struct dx_root_info *dx_info;
 	int csum_size = 0;
 
 	if (ext4_has_feature_metadata_csum(inode->i_sb))
@@ -2232,17 +2225,15 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 		return retval;
 	}
 
-	root = (struct dx_root *) bh->b_data;
-	if (!ext4_check_dx_root(dir, root)) {
+	dot_de = (struct ext4_dir_entry_2 *)bh->b_data;
+	dotdot_de = ext4_next_entry(dot_de, blocksize);
+	if (!ext4_check_dx_root(dir, dot_de, dotdot_de, &de)) {
 		brelse(bh);
 		return -EFSCORRUPTED;
 	}
 
 	/* The 0th block becomes the root, move the dirents out */
-	fde = &root->dotdot;
-	de = (struct ext4_dir_entry_2 *)((char *)fde +
-		ext4_rec_len_from_disk(fde->rec_len, blocksize));
-	len = ((char *) root) + (blocksize - csum_size) - (char *) de;
+	len = ((char *)dot_de) + (blocksize - csum_size) - (char *)de;
 
 	/* Allocate new block for the 0th block's dirents */
 	bh2 = ext4_append(handle, dir, &block);
@@ -2273,24 +2264,27 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 		ext4_initialize_dirent_tail(bh2, blocksize);
 
 	/* Initialize the root; the dot dirents already exist */
-	de = (struct ext4_dir_entry_2 *) (&root->dotdot);
-	de->rec_len = ext4_rec_len_to_disk(
-			blocksize - ext4_dir_rec_len(2, NULL), blocksize);
-	memset (&root->info, 0, sizeof(root->info));
-	root->info.info_length = sizeof(root->info);
+	dotdot_de->rec_len =
+		ext4_rec_len_to_disk(blocksize - le16_to_cpu(dot_de->rec_len),
+				     blocksize);
+
+	/* initialize hashing info */
+	dx_info = dx_get_dx_info(dot_de);
+	memset(dx_info, 0, sizeof(*dx_info));
+	dx_info->info_length = sizeof(*dx_info);
 	if (ext4_hash_in_dirent(dir))
-		root->info.hash_version = DX_HASH_SIPHASH;
+		dx_info->hash_version = DX_HASH_SIPHASH;
 	else
-		root->info.hash_version =
+		dx_info->hash_version =
 				EXT4_SB(dir->i_sb)->s_def_hash_version;
 
-	entries = root->entries;
+	entries = (void *)dx_info + sizeof(*dx_info);
 	dx_set_block(entries, 1);
 	dx_set_count(entries, 1);
-	dx_set_limit(entries, dx_root_limit(dir, sizeof(root->info)));
+	dx_set_limit(entries, dx_root_limit(dir, sizeof(*dx_info)));
 
 	/* Initialize as for dx_probe */
-	fname->hinfo.hash_version = root->info.hash_version;
+	fname->hinfo.hash_version = dx_info->hash_version;
 	if (fname->hinfo.hash_version <= DX_HASH_TEA)
 		fname->hinfo.hash_version += EXT4_SB(dir->i_sb)->s_hash_unsigned;
 	fname->hinfo.seed = EXT4_SB(dir->i_sb)->s_hash_seed;
@@ -2600,7 +2594,7 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname,
 			if (restart || err)
 				goto journal_error;
 		} else {
-			struct dx_root *dxroot;
+			struct dx_root_info *info;
 			memcpy((char *) entries2, (char *) entries,
 			       icount * sizeof(struct dx_entry));
 			dx_set_limit(entries2, dx_node_limit(dir));
@@ -2608,8 +2602,9 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname,
 			/* Set up root */
 			dx_set_count(entries, 1);
 			dx_set_block(entries + 0, newblock);
-			dxroot = (struct dx_root *)frames[0].bh->b_data;
-			dxroot->info.indirect_levels += 1;
+			info = dx_get_dx_info((struct ext4_dir_entry_2 *)
+					      frames[0].bh->b_data);
+			info->indirect_levels += 1;
 			dxtrace(printk(KERN_DEBUG
 				       "Creating %d level index...\n",
 				       dxroot->info.indirect_levels));
-- 
2.43.7

[PATCH v2 04/10] ext4: add dirdata format definitions and access helpers

[Artem Blagodarenko]

From: Artem Blagodarenko <artem.blagodarenko@gmail.com>

Define the on-disk format for ext4 directory entry extension data.

The upper four bits of de->file_type indicate the presence of
optional data stored after the filename NUL terminator.  This patch
defines flags for LUFID, 64-bit inode numbers, and casefold hash
data stored in that area.

Add struct ext4_dirent_data_header to describe variable-length
extension records and struct ext4_dirent_hash for hash storage used
by casefold and fscrypt.

Provide ext4_dirdata_next() to advance to the next extension record
and ext4_dirent_get_data_len() to compute the total extension data
length associated with a directory entry.

No functional changes.

Signed-off-by: Pravin Shelar <pravin.shelar@sun.com>
Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Reviewed-by: Andreas Dilger <adilger@diliger.ca>
---
 fs/ext4/ext4.h | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 01b1222b1454..c36c3bf54590 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2470,6 +2470,49 @@ struct ext4_dir_entry_tail {
 #define EXT4_FT_SYMLINK		7
 
 #define EXT4_FT_MAX		8
+#define EXT4_FT_MASK		0xf
+
+#if EXT4_FT_MAX > EXT4_FT_MASK
+#error "conflicting EXT4_FT_MAX and EXT4_FT_MASK"
+#endif
+
+/*
+ * d_type has 4 unused bits, so it can hold four types of data. These different
+ * types of data (e.g. fscypt hash, high 32 bits of 64-bit inode number) can be
+ * stored, in flag order, after file-name in ext4 dirent.
+ *
+ * These flags are added to d_type if ext4 dirent has extra data after
+ * filename. This data length is variable and length is stored in first byte
+ * of data. Data starts after filename NUL byte.
+ */
+#define EXT4_DIRENT_LUFID		0x10
+#define EXT4_DIRENT_INO64		0x20
+#define EXT4_DIRENT_CFHASH		0x40
+
+struct ext4_fid {
+	char    fid[16];     /* 128-bit unique file identifier */
+};
+
+struct ext4_dirent_data_header {
+	/* length of this header + the whole data blob */
+	__u8	ddh_length;
+} __packed;
+
+struct ext4_dirent_fid {
+	struct ext4_dirent_data_header df_header;
+	struct ext4_fid                df_fid[];
+};
+
+#define EXT4_LUFID_MAGIC    0xAD200907UL
+struct ext4_dentry_param {
+	__u32			edp_magic;	/* EXT4_LUFID_MAGIC */
+	struct ext4_dirent_fid	edp_dfid;
+};
+
+struct ext4_dirent_hash {
+	struct ext4_dirent_data_header	dh_header;
+	struct ext4_dir_entry_hash	dh_hash;
+} __packed;
 
 #define EXT4_FT_DIR_CSUM	0xDE
 
@@ -3917,6 +3960,12 @@ static inline void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
 		io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
 }
 
+/*
+ * Advance to the next dirdata record header starting from @ddh.
+ */
+#define ext4_dirdata_next(ddh) \
+	((struct ext4_dirent_data_header *)((char *)(ddh) + (ddh)->ddh_length))
+
 /*
  * ext4_dir_entry_is_tail() - Check if a directory entry is a tail entry.
  * @de: directory entry to check
@@ -3933,6 +3982,40 @@ static inline bool ext4_dir_entry_is_tail(struct ext4_dir_entry_2 *de)
 	       t->det_reserved_ft == EXT4_FT_DIR_CSUM;
 }
 
+/*
+ * ext4_dirent_get_data_len() - Compute the total dirdata length for an entry.
+ * @de: directory entry
+ *
+ * Computes the length of optional data stored after the filename (and its
+ * implicit NUL terminator).  Each extension is indicated by a bit in the
+ * high 4 bits of de->file_type; the first byte of each extension is its
+ * length (including that length byte itself).
+ *
+ * Returns 0 for tail entries and for entries with no dirdata.
+ */
+static inline int ext4_dirent_get_data_len(struct ext4_dir_entry_2 *de)
+{
+	__u8 extra_data_flags;
+	struct ext4_dirent_data_header *ddh;
+	int dlen = 0;
+
+	if (ext4_dir_entry_is_tail(de))
+		return 0;
+
+	extra_data_flags = (de->file_type & ~EXT4_FT_MASK) >> 4;
+	ddh = (struct ext4_dirent_data_header *)(de->name + de->name_len +
+						 1 /* NUL terminator */);
+
+	while (extra_data_flags) {
+		if (extra_data_flags & 1) {
+			dlen += ddh->ddh_length + (dlen == 0);
+			ddh = ext4_dirdata_next(ddh);
+		}
+		extra_data_flags >>= 1;
+	}
+	return dlen;
+}
+
 extern const struct iomap_ops ext4_iomap_ops;
 extern const struct iomap_ops ext4_iomap_report_ops;
 
-- 
2.43.7

[PATCH v2 05/10] ext4: preserve dirdata bits in get_dtype()

[Artem Blagodarenko]

From: Artem Blagodarenko <artem.blagodarenko@gmail.com>

Mask the filetype with EXT4_FT_MASK when indexing
ext4_filetype_table[] to avoid using dirdata bits as an index.

Preserve the extra bits
stored in the upper part of filetype and propagate them to the
returned dtype value.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 fs/ext4/ext4.h | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index c36c3bf54590..f833f6ef0040 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2960,12 +2960,15 @@ static const unsigned char ext4_filetype_table[] = {
 	DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
 };
 
-static inline  unsigned char get_dtype(struct super_block *sb, int filetype)
+static inline unsigned char get_dtype(struct super_block *sb, int filetype)
 {
-	if (!ext4_has_feature_filetype(sb) || filetype >= EXT4_FT_MAX)
+	unsigned char fl_index = filetype & EXT4_FT_MASK;
+
+	if (!ext4_has_feature_filetype(sb) || fl_index >= EXT4_FT_MAX)
 		return DT_UNKNOWN;
 
-	return ext4_filetype_table[filetype];
+	return (ext4_filetype_table[fl_index]) |
+		(filetype & ~EXT4_FT_MASK);
 }
 extern int ext4_check_all_de(struct inode *dir, struct buffer_head *bh,
 			     void *buf, int buf_size);
-- 
2.43.7

[PATCH v2 06/10] ext4: add ext4_dir_entry_len() and harden dirdata parsing

[Artem Blagodarenko]

From: Artem Blagodarenko <artem.blagodarenko@gmail.com>

Introduce ext4_dir_entry_len() helper to compute the required
rec_len for a directory entry, taking into account dirdata and
casefold+fscrypt hash space.

Convert ext4_dirent_get_data_len() to take the decoded rec_len
as an argument and add bounds checking when walking dirdata
extensions to avoid overruns on malformed entries.

Update dx_root_limit() to use ext4_dir_entry_len() instead of
open-coded ext4_dir_rec_len() for '.' and '..' entries.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 fs/ext4/ext4.h  | 45 ++++++++++++++++++++++++++++++++++++++++++---
 fs/ext4/namei.c | 23 +++++++++++++++--------
 2 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index f833f6ef0040..45e90b8be9e8 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3988,6 +3988,7 @@ static inline bool ext4_dir_entry_is_tail(struct ext4_dir_entry_2 *de)
 /*
  * ext4_dirent_get_data_len() - Compute the total dirdata length for an entry.
  * @de: directory entry
+ * @rec_len: the record length of the directory entry (decoded)
  *
  * Computes the length of optional data stored after the filename (and its
  * implicit NUL terminator).  Each extension is indicated by a bit in the
@@ -3996,22 +3997,41 @@ static inline bool ext4_dir_entry_is_tail(struct ext4_dir_entry_2 *de)
  *
  * Returns 0 for tail entries and for entries with no dirdata.
  */
-static inline int ext4_dirent_get_data_len(struct ext4_dir_entry_2 *de)
+static inline int ext4_dirent_get_data_len(struct ext4_dir_entry_2 *de,
+					   unsigned int rec_len)
 {
 	__u8 extra_data_flags;
 	struct ext4_dirent_data_header *ddh;
 	int dlen = 0;
+	unsigned int offset;
 
 	if (ext4_dir_entry_is_tail(de))
 		return 0;
 
 	extra_data_flags = (de->file_type & ~EXT4_FT_MASK) >> 4;
-	ddh = (struct ext4_dirent_data_header *)(de->name + de->name_len +
-						 1 /* NUL terminator */);
+	/* offset from start of entry to after filename + NUL */
+	offset = EXT4_BASE_DIR_LEN + de->name_len + 1;
 
+	/* bounds check: ensure we start reading within the entry */
+	if (offset >= rec_len)
+		return 0;
+
+	ddh = (struct ext4_dirent_data_header *)((char *)de + offset);
+ 
 	while (extra_data_flags) {
 		if (extra_data_flags & 1) {
+			/* bounds check before reading ddh_length */
+			if (offset + sizeof(*ddh) >
+			    rec_len)
+				return dlen;
+
+			/* validate ddh_length is reasonable */
+			if (ddh->ddh_length == 0 || ddh->ddh_length >
+			    rec_len - offset)
+				return dlen;
+
 			dlen += ddh->ddh_length + (dlen == 0);
+			offset += ddh->ddh_length;
 			ddh = ext4_dirdata_next(ddh);
 		}
 		extra_data_flags >>= 1;
@@ -4019,6 +4039,25 @@ static inline int ext4_dirent_get_data_len(struct ext4_dir_entry_2 *de)
 	return dlen;
 }
 
+/*
+ * ext4_dir_entry_len() - Compute the required rec_len for a directory entry.
+ * @de:  directory entry (used to read name_len and any dirdata length)
+ * @dir: directory inode (may be NULL for '.' and '..' entries)
+ *
+ * Returns the minimum record length needed to hold @de, rounded up to the
+ * directory alignment and including room for the casefold+fscrypt hash if
+ * the directory requires it.
+ */
+static inline unsigned int ext4_dir_entry_len(struct ext4_dir_entry_2 *de,
+					      const struct inode *dir)
+{
+	unsigned int blocksize = (dir && dir->i_sb) ? dir->i_sb->s_blocksize : 4096;
+	unsigned int rec_len = ext4_rec_len_from_disk(de->rec_len, blocksize);
+	unsigned int dirdata = ext4_dirent_get_data_len(de, rec_len);
+
+	return ext4_dir_rec_len(de->name_len + dirdata, dir);
+}
+
 extern const struct iomap_ops ext4_iomap_ops;
 extern const struct iomap_ops ext4_iomap_report_ops;
 
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 87d8cd2c6377..0635eac2de8d 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -570,11 +570,15 @@ static inline void dx_set_limit(struct dx_entry *entries, unsigned value)
 	((struct dx_countlimit *) entries)->limit = cpu_to_le16(value);
 }
 
-static inline unsigned dx_root_limit(struct inode *dir, unsigned infosize)
+static inline unsigned dx_root_limit(struct inode *dir,
+	struct ext4_dir_entry_2 *dot_de)
 {
-	unsigned int entry_space = dir->i_sb->s_blocksize -
-			ext4_dir_rec_len(1, NULL) -
-			ext4_dir_rec_len(2, NULL) - infosize;
+	struct dx_root_info *info;
+	unsigned int entry_space;
+
+	info = dx_get_dx_info(dot_de);
+	entry_space = dir->i_sb->s_blocksize - ((char *)info - (char *)dot_de) -
+		info->info_length;
 
 	if (ext4_has_feature_metadata_csum(dir->i_sb))
 		entry_space -= sizeof(struct dx_tail);
@@ -850,10 +854,13 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
 
 	entries = (struct dx_entry *)(((char *)info) + info->info_length);
 
-	if (dx_get_limit(entries) != dx_root_limit(dir, info->info_length)) {
+	if (dx_get_limit(entries) !=
+	    dx_root_limit(dir, (struct ext4_dir_entry_2 *)frame->bh->b_data)) {
 		ext4_warning_inode(dir, "dx entry: limit %u != root limit %u",
 				   dx_get_limit(entries),
-				   dx_root_limit(dir, info->info_length));
+				   dx_root_limit(dir,
+				   (struct ext4_dir_entry_2 *)frame->bh->b_data
+				   ));
 		goto fail;
 	}
 
@@ -2278,10 +2285,10 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 		dx_info->hash_version =
 				EXT4_SB(dir->i_sb)->s_def_hash_version;
 
-	entries = (void *)dx_info + sizeof(*dx_info);
+	entries = (void *)dx_info + dx_info->info_length;
 	dx_set_block(entries, 1);
 	dx_set_count(entries, 1);
-	dx_set_limit(entries, dx_root_limit(dir, sizeof(*dx_info)));
+	dx_set_limit(entries, dx_root_limit(dir, dot_de));
 
 	/* Initialize as for dx_probe */
 	fname->hinfo.hash_version = dx_info->hash_version;
-- 
2.43.7

[PATCH v2 07/10] ext4: rename ext4_dir_rec_len() and clarify dirdata usage

[Artem Blagodarenko]

From: Artem Blagodarenko <artem.blagodarenko@gmail.com>

Rename ext4_dir_rec_len() to ext4_dirent_rec_len() to better
reflect that it computes the record length for a directory
entry based on the provided name length.

Update the comment to clarify handling of dirdata-enabled
directories and document the use of ext4_dir_entry_len()
when dirdata is present.

No functional changes.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 fs/ext4/dir.c    |  9 ++++-----
 fs/ext4/ext4.h   | 14 ++++++++++----
 fs/ext4/inline.c | 14 +++++++-------
 fs/ext4/namei.c  | 39 ++++++++++++++++++++++-----------------
 4 files changed, 43 insertions(+), 33 deletions(-)

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 17edd678fa87..012687822b82 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -89,16 +89,15 @@ int __ext4_check_dir_entry(const char *function, unsigned int line,
 	bool fake = is_fake_dir_entry(de);
 	bool has_csum = ext4_has_feature_metadata_csum(dir->i_sb);
 
-	if (unlikely(rlen < ext4_dir_rec_len(1, fake ? NULL : dir)))
+	if (unlikely(rlen < ext4_dirent_rec_len(1, fake ? NULL : dir)))
 		error_msg = "rec_len is smaller than minimal";
 	else if (unlikely(rlen % 4 != 0))
 		error_msg = "rec_len % 4 != 0";
-	else if (unlikely(rlen < ext4_dir_rec_len(de->name_len,
-							fake ? NULL : dir)))
+	else if (unlikely(rlen < ext4_dir_entry_len(de, fake ? NULL : dir)))
 		error_msg = "rec_len is too small for name_len";
 	else if (unlikely(next_offset > size))
 		error_msg = "directory entry overrun";
-	else if (unlikely(next_offset > size - ext4_dir_rec_len(1,
+	else if (unlikely(next_offset > size - ext4_dirent_rec_len(1,
 						  has_csum ? NULL : dir) &&
 			  next_offset != size))
 		error_msg = "directory entry too close to block end";
@@ -245,7 +244,7 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
 				 * failure will be detected in the
 				 * dirent test below. */
 				if (ext4_rec_len_from_disk(de->rec_len,
-					sb->s_blocksize) < ext4_dir_rec_len(1,
+					sb->s_blocksize) < ext4_dirent_rec_len(1,
 									inode))
 					break;
 				i += ext4_rec_len_from_disk(de->rec_len,
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 45e90b8be9e8..066c49fe3266 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2530,11 +2530,16 @@ struct ext4_dirent_hash {
  * casefolded and encrypted need to store the hash as well, so we add room for
  * ext4_extended_dir_entry_2. For all entries related to '.' or '..' you should
  * pass NULL for dir, as those entries do not use the extra fields.
+ *
+ * For directories with the dirdata feature, extra data may follow the filename.
+ * Use ext4_dir_entry_len() to compute the length of a directory entry
+ * including any dirdata, or ext4_dirent_rec_len() directly when the total
+ * name_len (including dirdata length) is already known.
  */
-static inline unsigned int ext4_dir_rec_len(__u8 name_len,
+static inline unsigned int ext4_dirent_rec_len(unsigned int name_len,
 						const struct inode *dir)
 {
-	int rec_len = (name_len + 8 + EXT4_DIR_ROUND);
+	unsigned int rec_len = (name_len + 8 + EXT4_DIR_ROUND);
 
 	if (dir && ext4_hash_in_dirent(dir))
 		rec_len += sizeof(struct ext4_dir_entry_hash);
@@ -2942,7 +2947,8 @@ extern void ext4_htree_free_dir_info(struct dir_private_info *p);
 extern int ext4_find_dest_de(struct inode *dir, struct buffer_head *bh,
 			     void *buf, int buf_size,
 			     struct ext4_filename *fname,
-			     struct ext4_dir_entry_2 **dest_de);
+			     struct ext4_dir_entry_2 **dest_de,
+			     int dlen);
 void ext4_insert_dentry(struct inode *dir, struct inode *inode,
 			struct ext4_dir_entry_2 *de,
 			int buf_size,
@@ -4055,7 +4061,7 @@ static inline unsigned int ext4_dir_entry_len(struct ext4_dir_entry_2 *de,
 	unsigned int rec_len = ext4_rec_len_from_disk(de->rec_len, blocksize);
 	unsigned int dirdata = ext4_dirent_get_data_len(de, rec_len);
 
-	return ext4_dir_rec_len(de->name_len + dirdata, dir);
+	return ext4_dirent_rec_len(de->name_len + dirdata, dir);
 }
 
 extern const struct iomap_ops ext4_iomap_ops;
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 8045e4ff270c..5b3faacdf143 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -977,7 +977,7 @@ static int ext4_add_dirent_to_inline(handle_t *handle,
 	struct ext4_dir_entry_2 *de;
 
 	err = ext4_find_dest_de(dir, iloc->bh, inline_start,
-				inline_size, fname, &de);
+				inline_size, fname, &de, 0);
 	if (err)
 		return err;
 
@@ -1055,7 +1055,7 @@ static int ext4_update_inline_dir(handle_t *handle, struct inode *dir,
 	int old_size = EXT4_I(dir)->i_inline_size - EXT4_MIN_INLINE_DATA_SIZE;
 	int new_size = get_max_inline_xattr_value_size(dir, iloc);
 
-	if (new_size - old_size <= ext4_dir_rec_len(1, NULL))
+	if (new_size - old_size <= ext4_dirent_rec_len(1, NULL))
 		return -ENOSPC;
 
 	ret = ext4_update_inline_data(handle, dir,
@@ -1309,7 +1309,7 @@ int ext4_inlinedir_to_tree(struct file *dir_file,
 			fake.name_len = 1;
 			memcpy(fake.name, ".", 2);
 			fake.rec_len = ext4_rec_len_to_disk(
-					  ext4_dir_rec_len(fake.name_len, NULL),
+					  ext4_dirent_rec_len(fake.name_len, NULL),
 					  inline_size);
 			ext4_set_de_type(inode->i_sb, &fake, S_IFDIR);
 			de = &fake;
@@ -1319,7 +1319,7 @@ int ext4_inlinedir_to_tree(struct file *dir_file,
 			fake.name_len = 2;
 			memcpy(fake.name, "..", 3);
 			fake.rec_len = ext4_rec_len_to_disk(
-					  ext4_dir_rec_len(fake.name_len, NULL),
+					  ext4_dirent_rec_len(fake.name_len, NULL),
 					  inline_size);
 			ext4_set_de_type(inode->i_sb, &fake, S_IFDIR);
 			de = &fake;
@@ -1427,8 +1427,8 @@ int ext4_read_inline_dir(struct file *file,
 	 * So we will use extra_offset and extra_size to indicate them
 	 * during the inline dir iteration.
 	 */
-	dotdot_offset = ext4_dir_rec_len(1, NULL);
-	dotdot_size = dotdot_offset + ext4_dir_rec_len(2, NULL);
+	dotdot_offset = ext4_dirent_rec_len(1, NULL);
+	dotdot_size = dotdot_offset + ext4_dirent_rec_len(2, NULL);
 	extra_offset = dotdot_size - EXT4_INLINE_DOTDOT_SIZE;
 	extra_size = extra_offset + inline_size;
 
@@ -1463,7 +1463,7 @@ int ext4_read_inline_dir(struct file *file,
 			 * failure will be detected in the
 			 * dirent test below. */
 			if (ext4_rec_len_from_disk(de->rec_len, extra_size)
-				< ext4_dir_rec_len(1, NULL))
+				< ext4_dirent_rec_len(1, NULL))
 				break;
 			i += ext4_rec_len_from_disk(de->rec_len,
 						    extra_size);
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 0635eac2de8d..cd20b1094134 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -522,10 +522,10 @@ ext4_next_entry(struct ext4_dir_entry_2 *p, unsigned long blocksize)
 static struct dx_root_info *dx_get_dx_info(void *de_buf)
 {
 	/* get dotdot first */
-	de_buf = de_buf + ext4_dir_rec_len(1, NULL);
+	de_buf += ext4_dir_entry_len(de_buf, NULL);
 
 	/* dx root info is after dotdot entry */
-	de_buf = de_buf + ext4_dir_rec_len(2, NULL);
+	de_buf += ext4_dir_entry_len(de_buf, NULL);
 
 	return (struct dx_root_info *)de_buf;
 }
@@ -588,7 +588,7 @@ static inline unsigned dx_root_limit(struct inode *dir,
 static inline unsigned dx_node_limit(struct inode *dir)
 {
 	unsigned int entry_space = dir->i_sb->s_blocksize -
-			ext4_dir_rec_len(0, dir);
+			ext4_dirent_rec_len(0, dir);
 
 	if (ext4_has_feature_metadata_csum(dir->i_sb))
 		entry_space -= sizeof(struct dx_tail);
@@ -1058,7 +1058,7 @@ static int htree_dirblock_to_tree(struct file *dir_file,
 	/* csum entries are not larger in the casefolded encrypted case */
 	top = (struct ext4_dir_entry_2 *) ((char *) de +
 					   dir->i_sb->s_blocksize -
-					   ext4_dir_rec_len(0,
+					   ext4_dirent_rec_len(0,
 							   csum ? NULL : dir));
 	/* Check if the directory is encrypted */
 	if (IS_ENCRYPTED(dir)) {
@@ -1852,7 +1852,7 @@ dx_move_dirents(struct inode *dir, char *from, char *to,
 	while (count--) {
 		struct ext4_dir_entry_2 *de = (struct ext4_dir_entry_2 *)
 						(from + (map->offs<<2));
-		rec_len = ext4_dir_rec_len(de->name_len, dir);
+		rec_len = ext4_dir_entry_len(de, dir);
 
 		memcpy (to, de, rec_len);
 		((struct ext4_dir_entry_2 *) to)->rec_len =
@@ -1885,7 +1885,7 @@ static struct ext4_dir_entry_2 *dx_pack_dirents(struct inode *dir, char *base,
 	while ((char*)de < base + blocksize) {
 		next = ext4_next_entry(de, blocksize);
 		if (de->inode && de->name_len) {
-			rec_len = ext4_dir_rec_len(de->name_len, dir);
+			rec_len = ext4_dir_entry_len(de, dir);
 			if (de > to)
 				memmove(to, de, rec_len);
 			to->rec_len = ext4_rec_len_to_disk(rec_len, blocksize);
@@ -2037,10 +2037,11 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
 int ext4_find_dest_de(struct inode *dir, struct buffer_head *bh,
 		      void *buf, int buf_size,
 		      struct ext4_filename *fname,
-		      struct ext4_dir_entry_2 **dest_de)
+		      struct ext4_dir_entry_2 **dest_de,
+		      int dlen)
 {
 	struct ext4_dir_entry_2 *de;
-	unsigned short reclen = ext4_dir_rec_len(fname_len(fname), dir);
+	unsigned short reclen = ext4_dirent_rec_len(fname_len(fname) + dlen, dir);
 	int nlen, rlen;
 	unsigned int offset = 0;
 	char *top;
@@ -2053,7 +2054,7 @@ int ext4_find_dest_de(struct inode *dir, struct buffer_head *bh,
 			return -EFSCORRUPTED;
 		if (ext4_match(dir, fname, de))
 			return -EEXIST;
-		nlen = ext4_dir_rec_len(de->name_len, dir);
+		nlen = ext4_dir_entry_len(de, dir);
 		rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
 		if ((de->inode ? rlen - nlen : rlen) >= reclen)
 			break;
@@ -2076,7 +2077,7 @@ void ext4_insert_dentry(struct inode *dir,
 
 	int nlen, rlen;
 
-	nlen = ext4_dir_rec_len(de->name_len, dir);
+	nlen = ext4_dir_entry_len(de, dir);
 	rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
 	if (de->inode) {
 		struct ext4_dir_entry_2 *de1 =
@@ -2114,14 +2115,18 @@ static int add_dirent_to_buf(handle_t *handle, struct ext4_filename *fname,
 {
 	unsigned int	blocksize = dir->i_sb->s_blocksize;
 	int		csum_size = 0;
-	int		err, err2;
+	int		err, err2, dlen = 0;
+	unsigned char	*data = NULL;
 
+	/* Deliver data in any appropriate way here. Now it is NULL */
 	if (ext4_has_feature_metadata_csum(inode->i_sb))
 		csum_size = sizeof(struct ext4_dir_entry_tail);
 
 	if (!de) {
+		if (data)
+			dlen = (*data) + 1;
 		err = ext4_find_dest_de(dir, bh, bh->b_data,
-					blocksize - csum_size, fname, &de);
+					blocksize - csum_size, fname, &de, dlen);
 		if (err)
 			return err;
 	}
@@ -2930,7 +2935,7 @@ int ext4_init_dirblock(handle_t *handle, struct inode *inode,
 
 	de->inode = cpu_to_le32(inode->i_ino);
 	de->name_len = 1;
-	de->rec_len = ext4_rec_len_to_disk(ext4_dir_rec_len(de->name_len, NULL),
+	de->rec_len = ext4_rec_len_to_disk(ext4_dirent_rec_len(de->name_len, NULL),
 					   blocksize);
 	memcpy(de->name, ".", 2);
 	ext4_set_de_type(inode->i_sb, de, S_IFDIR);
@@ -2942,7 +2947,7 @@ int ext4_init_dirblock(handle_t *handle, struct inode *inode,
 	ext4_set_de_type(inode->i_sb, de, S_IFDIR);
 	if (inline_buf) {
 		de->rec_len = ext4_rec_len_to_disk(
-					ext4_dir_rec_len(de->name_len, NULL),
+					ext4_dirent_rec_len(de->name_len, NULL),
 					blocksize);
 		de = ext4_next_entry(de, blocksize);
 		header_size = (char *)de - bh->b_data;
@@ -2951,7 +2956,7 @@ int ext4_init_dirblock(handle_t *handle, struct inode *inode,
 			blocksize - csum_size);
 	} else {
 		de->rec_len = ext4_rec_len_to_disk(blocksize -
-					(csum_size + ext4_dir_rec_len(1, NULL)),
+					(csum_size + ext4_dirent_rec_len(1, NULL)),
 					blocksize);
 	}
 
@@ -3074,8 +3079,8 @@ bool ext4_empty_dir(struct inode *inode)
 	}
 
 	sb = inode->i_sb;
-	if (inode->i_size < ext4_dir_rec_len(1, NULL) +
-					ext4_dir_rec_len(2, NULL)) {
+	if (inode->i_size < ext4_dirent_rec_len(1, NULL) +
+					ext4_dirent_rec_len(2, NULL)) {
 		EXT4_ERROR_INODE(inode, "invalid size");
 		return false;
 	}
-- 
2.43.7

[PATCH v2 08/10] ext4: dirdata feature

[Artem Blagodarenko]

From: Artem Blagodarenko <artem.blagodarenko@gmail.com>

When fscrypt and casefold are enabled together for a directory,
all ext4_dir_entry[_2] in that directory store a n 8-byte hash
of the filename after 'name' between 'name_len' and 'rec_len'.

However, there is no clear indication there is important data
stored in these bytes, which are only for padding and alignment
in other directory entries.  This adds complexity to code handling
the on-disk directory entries, and there is no provision for other
metadata to be stored in each dir entry after 'name'.

The dirdata feature adds a mechanism to store multiple metadata
entries in each dir entry after 'name' (including the fchash).
The unused high 4 bits of 'file_type' are used to indicate whether
additional data fields are stored after 'name'.  If a bit is set,
the corresponding dirdata record is present, starting after a NUL
filename terminator.  If present, a record starts with a 1-byte
length (including the length byte itself) and the data immediately
follows the length byte without any alignment.

This allows up to four different dirdata records to be stored in
each entry, and allows unhandled record bytes to be skipped without
having to process the contents, providing forward compatibility.

If and when the fourth and last dirdata record is needed, it is
recommended to further subdivide it into sub-records, with
the first byte being the total length, and then there being a
second byte that gives the sub-record length, etc. as long as
the total record length is less than 255 bytes.  However, this
would not affect compatibility with the current code since the
record length would allow it to be skipped without processing.

Signed-off-by: Pravin Shelar <pravin.shelar@sun.com>
Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 fs/ext4/ext4.h   | 27 +++++++++++++++++++++------
 fs/ext4/inline.c | 19 +++++++++++++++----
 fs/ext4/namei.c  | 43 +++++++++++++++++++++----------------------
 fs/ext4/sysfs.c  |  2 ++
 4 files changed, 59 insertions(+), 32 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 066c49fe3266..ef99e4fa99d7 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2248,6 +2248,7 @@ EXT4_FEATURE_INCOMPAT_FUNCS(casefold,		CASEFOLD)
 					 EXT4_FEATURE_INCOMPAT_FLEX_BG| \
 					 EXT4_FEATURE_INCOMPAT_EA_INODE| \
 					 EXT4_FEATURE_INCOMPAT_MMP | \
+					 EXT4_FEATURE_INCOMPAT_DIRDATA | \
 					 EXT4_FEATURE_INCOMPAT_INLINE_DATA | \
 					 EXT4_FEATURE_INCOMPAT_ENCRYPT | \
 					 EXT4_FEATURE_INCOMPAT_CASEFOLD | \
@@ -2949,10 +2950,18 @@ extern int ext4_find_dest_de(struct inode *dir, struct buffer_head *bh,
 			     struct ext4_filename *fname,
 			     struct ext4_dir_entry_2 **dest_de,
 			     int dlen);
-void ext4_insert_dentry(struct inode *dir, struct inode *inode,
-			struct ext4_dir_entry_2 *de,
-			int buf_size,
-			struct ext4_filename *fname);
+void ext4_insert_dentry_data(struct inode *dir, struct inode *inode,
+			     struct ext4_dir_entry_2 *de,
+			     int buf_size,
+			     struct ext4_filename *fname,
+			     void *data);
+static inline void ext4_insert_dentry(struct inode *dir, struct inode *inode,
+				      struct ext4_dir_entry_2 *de,
+				      int buf_size,
+				      struct ext4_filename *fname)
+{
+	ext4_insert_dentry_data(dir, inode, de, buf_size, fname, NULL);
+}
 static inline void ext4_update_dx_flag(struct inode *inode)
 {
 	if (!ext4_has_feature_dir_index(inode->i_sb) &&
@@ -3196,8 +3205,14 @@ extern int ext4_ext_migrate(struct inode *);
 extern int ext4_ind_migrate(struct inode *inode);
 
 /* namei.c */
-extern int ext4_init_new_dir(handle_t *handle, struct inode *dir,
-			     struct inode *inode);
+extern int ext4_init_new_dir_data(handle_t *handle, struct inode *dir,
+				  struct inode *inode,
+				  const void *data1, const void *data2);
+static inline int ext4_init_new_dir(handle_t *handle, struct inode *dir,
+				    struct inode *inode)
+{
+	return ext4_init_new_dir_data(handle, dir, inode, NULL, NULL);
+}
 extern int ext4_dirblock_csum_verify(struct inode *inode,
 				     struct buffer_head *bh);
 extern int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 5b3faacdf143..c57a8ebe4f94 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -973,11 +973,16 @@ static int ext4_add_dirent_to_inline(handle_t *handle,
 				     struct ext4_iloc *iloc,
 				     void *inline_start, int inline_size)
 {
-	int		err;
+	int		err, dlen = 0;
 	struct ext4_dir_entry_2 *de;
+	unsigned char *data = NULL;
+
+	/* Deliver data in any appropriate way here. Now it is NULL */
+	if (data)
+		dlen = (*data) + 1;
 
 	err = ext4_find_dest_de(dir, iloc->bh, inline_start,
-				inline_size, fname, &de, 0);
+				inline_size, fname, &de, dlen);
 	if (err)
 		return err;
 
@@ -986,7 +991,7 @@ static int ext4_add_dirent_to_inline(handle_t *handle,
 					    EXT4_JTR_NONE);
 	if (err)
 		return err;
-	ext4_insert_dentry(dir, inode, de, inline_size, fname);
+	ext4_insert_dentry_data(dir, inode, de, inline_size, fname, NULL);
 
 	ext4_show_inline_dir(dir, iloc->bh, inline_start, inline_size);
 
@@ -1326,7 +1331,13 @@ int ext4_inlinedir_to_tree(struct file *dir_file,
 			pos = EXT4_INLINE_DOTDOT_SIZE;
 		} else {
 			de = (struct ext4_dir_entry_2 *)(dir_buf + pos);
-			pos += ext4_rec_len_from_disk(de->rec_len, inline_size);
+			/* Use ext4_dir_entry_len to account for dirdata extensions */
+			pos += ext4_dir_entry_len(de, dir);
+			/* Validate pos doesn't exceed buffer to prevent use-after-free */
+			if (pos > inline_size) {
+				ret = count;
+				goto out;
+			}
 			if (ext4_check_dir_entry(inode, dir_file, de,
 					 iloc.bh, dir_buf,
 					 inline_size, pos)) {
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index cd20b1094134..40a3394f7eac 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -401,23 +401,24 @@ static struct dx_countlimit *get_dx_countlimit(struct inode *inode,
 {
 	struct ext4_dir_entry_2 *de;
 	struct dx_root_info *root;
-	int count_offset;
+	int count_offset, dotdot_rec_len;
 	int blocksize = EXT4_BLOCK_SIZE(inode->i_sb);
 	unsigned int rlen = ext4_rec_len_from_disk(dirent->rec_len, blocksize);
 
-	if (rlen == blocksize)
+	if (rlen == blocksize) {
 		count_offset = sizeof(struct dx_node);
-	else if (rlen == 12) {
-		de = (struct ext4_dir_entry_2 *)(((void *)dirent) + 12);
-		if (ext4_rec_len_from_disk(de->rec_len, blocksize) != blocksize - 12)
+	} else {
+		de = (struct ext4_dir_entry_2 *)(((char *)dirent) + rlen);
+		if (le16_to_cpu(de->rec_len) != (blocksize - rlen))
 			return NULL;
-		root = (struct dx_root_info *)(((void *)de + 12));
+		/* de->rec_len covers whole dx_root block, calculate actual length */
+		dotdot_rec_len = ext4_dir_entry_len(de, NULL);
+		root = (struct dx_root_info *)(((char *)de + dotdot_rec_len));
 		if (root->reserved_zero ||
 		    root->info_length != sizeof(struct dx_root_info))
 			return NULL;
-		count_offset = 32;
-	} else
-		return NULL;
+		count_offset = root->info_length + rlen + dotdot_rec_len;
+	}
 
 	if (offset)
 		*offset = count_offset;
@@ -698,7 +699,7 @@ static struct stats dx_show_leaf(struct inode *dir,
 				       (unsigned) ((char *) de - base));
 #endif
 			}
-			space += ext4_dir_rec_len(de->name_len, dir);
+			space += ext4_dir_entry_len(de, dir);
 			names++;
 		}
 		de = ext4_next_entry(de, size);
@@ -2068,13 +2069,10 @@ int ext4_find_dest_de(struct inode *dir, struct buffer_head *bh,
 	return 0;
 }
 
-void ext4_insert_dentry(struct inode *dir,
-			struct inode *inode,
-			struct ext4_dir_entry_2 *de,
-			int buf_size,
-			struct ext4_filename *fname)
+void ext4_insert_dentry_data(struct inode *dir, struct inode *inode,
+			     struct ext4_dir_entry_2 *de, int buf_size,
+			     struct ext4_filename *fname, void *data)
 {
-
 	int nlen, rlen;
 
 	nlen = ext4_dir_entry_len(de, dir);
@@ -2116,15 +2114,15 @@ static int add_dirent_to_buf(handle_t *handle, struct ext4_filename *fname,
 	unsigned int	blocksize = dir->i_sb->s_blocksize;
 	int		csum_size = 0;
 	int		err, err2, dlen = 0;
-	unsigned char	*data = NULL;
+	struct ext4_dirent_fid *dfid = NULL;
 
 	/* Deliver data in any appropriate way here. Now it is NULL */
 	if (ext4_has_feature_metadata_csum(inode->i_sb))
 		csum_size = sizeof(struct ext4_dir_entry_tail);
 
 	if (!de) {
-		if (data)
-			dlen = (*data) + 1;
+		if (dfid)
+			dlen = dfid->df_header.ddh_length;
 		err = ext4_find_dest_de(dir, bh, bh->b_data,
 					blocksize - csum_size, fname, &de, dlen);
 		if (err)
@@ -2139,7 +2137,7 @@ static int add_dirent_to_buf(handle_t *handle, struct ext4_filename *fname,
 	}
 
 	/* By now the buffer is marked for journaling */
-	ext4_insert_dentry(dir, inode, de, blocksize, fname);
+	ext4_insert_dentry_data(dir, inode, de, blocksize, fname, dfid);
 
 	/*
 	 * XXX shouldn't update any times until successful
@@ -2968,8 +2966,9 @@ int ext4_init_dirblock(handle_t *handle, struct inode *inode,
 	return ext4_handle_dirty_dirblock(handle, inode, bh);
 }
 
-int ext4_init_new_dir(handle_t *handle, struct inode *dir,
-			     struct inode *inode)
+int ext4_init_new_dir_data(handle_t *handle, struct inode *dir,
+			   struct inode *inode,
+			   const void *data1, const void *data2)
 {
 	struct buffer_head *dir_block = NULL;
 	ext4_lblk_t block = 0;
diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index 923b375e017f..80074fb15ee9 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -362,6 +362,7 @@ EXT4_ATTR_FEATURE(verity);
 #endif
 EXT4_ATTR_FEATURE(metadata_csum_seed);
 EXT4_ATTR_FEATURE(fast_commit);
+EXT4_ATTR_FEATURE(dirdata);
 #if IS_ENABLED(CONFIG_UNICODE) && defined(CONFIG_FS_ENCRYPTION)
 EXT4_ATTR_FEATURE(encrypted_casefold);
 #endif
@@ -385,6 +386,7 @@ static struct attribute *ext4_feat_attrs[] = {
 #endif
 	ATTR_LIST(metadata_csum_seed),
 	ATTR_LIST(fast_commit),
+	ATTR_LIST(dirdata),
 #if IS_ENABLED(CONFIG_UNICODE) && defined(CONFIG_FS_ENCRYPTION)
 	ATTR_LIST(encrypted_casefold),
 #endif
-- 
2.43.7

[PATCH v2 09/10] ext4: add dirdata set/get helpers

[Artem Blagodarenko]

From: Artem Blagodarenko <artem.blagodarenko@gmail.com>

Add helpers to set and retrieve dirdata payload and hook them up at
the appropriate call sites.

Enable dirdata for casefold+encryption hashes and storing unique
128-bit file identifier in the directory entry for testing.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 foofile.txt      |   0
 fs/ext4/ext4.h   |   4 +
 fs/ext4/inline.c |   6 +-
 fs/ext4/namei.c  | 196 ++++++++++++++++++++++++++++++++++++++++-------
 4 files changed, 176 insertions(+), 30 deletions(-)

diff --git a/foofile.txt b/foofile.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ef99e4fa99d7..defa18d98c74 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3787,6 +3787,10 @@ extern int __ext4_unlink(struct inode *dir, const struct qstr *d_name,
 			 struct inode *inode, struct dentry *dentry);
 extern int __ext4_link(struct inode *dir, struct inode *inode,
 		       const struct qstr *d_name, struct dentry *dentry);
+extern unsigned char ext4_dirdata_get(struct ext4_dir_entry_2 *de,
+				      struct inode *dir,
+				      struct ext4_dirent_fid  *lufid,
+				      struct dx_hash_info *hinfo);
 
 #define S_SHIFT 12
 static const unsigned char ext4_type_by_mode[(S_IFMT >> S_SHIFT) + 1] = {
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index c57a8ebe4f94..71c395c9a162 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -1346,10 +1346,8 @@ int ext4_inlinedir_to_tree(struct file *dir_file,
 			}
 		}
 
-		if (ext4_hash_in_dirent(dir)) {
-			hinfo->hash = EXT4_DIRENT_HASH(de);
-			hinfo->minor_hash = EXT4_DIRENT_MINOR_HASH(de);
-		} else {
+		if (!(ext4_dirdata_get(de, dir, NULL, hinfo) &
+							EXT4_DIRENT_CFHASH)) {
 			err = ext4fs_dirhash(dir, de->name, de->name_len, hinfo);
 			if (err) {
 				ret = err;
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 40a3394f7eac..c799f87d7459 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1084,22 +1084,22 @@ static int htree_dirblock_to_tree(struct file *dir_file,
 			/* silently ignore the rest of the block */
 			break;
 		}
-		if (ext4_hash_in_dirent(dir)) {
-			if (de->name_len && de->inode) {
-				hinfo->hash = EXT4_DIRENT_HASH(de);
-				hinfo->minor_hash = EXT4_DIRENT_MINOR_HASH(de);
-			} else {
-				hinfo->hash = 0;
-				hinfo->minor_hash = 0;
-			}
+		if (de->name_len && de->inode) {
+			/* check for saved hash first, or generate it from name */
+			if (!(ext4_dirdata_get(de, dir, NULL, hinfo) &
+			      EXT4_DIRENT_CFHASH)) {
+				err = ext4fs_dirhash(dir, de->name,
+						     de->name_len, hinfo);
+				if (err < 0) {
+					count = err;
+					goto errout;
+				}
+			 }
 		} else {
-			err = ext4fs_dirhash(dir, de->name,
-					     de->name_len, hinfo);
-			if (err < 0) {
-				count = err;
-				goto errout;
-			}
+			hinfo->hash = 0;
+			hinfo->minor_hash = 0;
 		}
+
 		if ((hinfo->hash < start_hash) ||
 		    ((hinfo->hash == start_hash) &&
 		     (hinfo->minor_hash < start_minor_hash)))
@@ -1277,9 +1277,160 @@ static inline int search_dirblock(struct buffer_head *bh,
  */
 
 /*
- * Create map of hash values, offsets, and sizes, stored at end of block.
- * Returns number of entries mapped.
+ * ext4_dirdata_get() - Read dirdata fields from a directory entry.
+ * @de:         directory entry
+ * @dir:        directory inode (used for fscrypt+casefold hash fallback)
+ * @dfid:      if non-NULL and EXT4_DIRENT_LUFID is set, LUFID data is copied
+ * 		here
+ * @hinfo:	if non-NULL, receives the casefold hash and minor hash
+ *
+ * Reads any dirdata stored in @de.  If the dirdata feature is not enabled,
+ * falls back to reading the hash stored inline after the filename (for
+ * compatibility with the older casefold+fscrypt format).
+ *
+ * Returns a bitmask of EXT4_DIRENT_* flags indicating which fields were read.
  */
+unsigned char ext4_dirdata_get(struct ext4_dir_entry_2 *de, struct inode *dir,
+			       struct ext4_dirent_fid *dfid,
+			       struct dx_hash_info *hinfo)
+{
+	unsigned char ret = 0;
+	unsigned int data_offset = de->name_len + 1;
+
+	if (data_offset > de->rec_len)
+		return ret;
+
+	/* compatibility: hash stored inline after filename (no dirdata) */
+	if (hinfo && !ext4_has_feature_dirdata(dir->i_sb) &&
+	    ext4_hash_in_dirent(dir)) {
+		hinfo->hash = EXT4_DIRENT_HASH(de);
+		hinfo->minor_hash = EXT4_DIRENT_MINOR_HASH(de);
+		ret |= EXT4_DIRENT_CFHASH;
+
+		return ret;
+	}
+
+	/*  EXT4_DIRENT_* are not expected without flag in i_sb */
+	if (de->file_type & EXT4_DIRENT_LUFID) {
+		struct ext4_dirent_fid *dfid =
+			(struct ext4_dirent_fid *)(de->name + data_offset);
+		unsigned int dlen;
+
+		if (data_offset + sizeof(dfid->df_header) > de->rec_len)
+			return ret;
+
+		dlen = dfid->df_header.ddh_length;
+		if (dlen < sizeof(*dfid) || data_offset + dlen > de->rec_len)
+			return ret;
+
+		if (dfid) {
+			memcpy(dfid, dfid->df_fid, dfid->df_header.ddh_length);
+			ret |= EXT4_DIRENT_LUFID;
+		}
+		data_offset += dlen;
+	}
+
+	/* Skip INO64 for now*/
+	if (de->file_type & EXT4_DIRENT_INO64) {
+		struct ext4_dirent_data_header *ddh =
+		       (struct ext4_dirent_data_header *)(de->name + data_offset);
+		unsigned int dlen;
+
+		if (data_offset + sizeof(*ddh) > de->rec_len)
+			return ret;
+
+		dlen = ddh->ddh_length;
+		if (dlen < sizeof(*ddh) || data_offset + dlen > de->rec_len)
+			return ret;
+
+		data_offset += dlen;
+	}
+
+	if (!hinfo)
+		return ret;
+
+	if (de->file_type & EXT4_DIRENT_CFHASH) {
+		struct ext4_dirent_hash *dh =
+			(struct ext4_dirent_hash *)(de->name + data_offset);
+		unsigned int dlen;
+
+		dlen = dh->dh_header.ddh_length;
+		if (dlen < sizeof(*dh) || data_offset + dlen > de->rec_len)
+			return ret;
+
+		hinfo->hash = le32_to_cpu(dh->dh_hash.hash);
+		hinfo->minor_hash = le32_to_cpu(dh->dh_hash.minor_hash);
+		ret |= EXT4_DIRENT_CFHASH;
+	}
+
+	return ret;
+}
+
+/*
+ * ext4_dirdata_set() - Write dirdata fields into a directory entry.
+ * @de:    directory entry (name must already be set)
+ * @dir:   directory inode
+ * @data:  LUFID data to store (or NULL)
+ * @fname: filename info carrying the casefold hash
+ *
+ * Writes any required dirdata into @de after the filename.  If the dirdata
+ * feature is not enabled, falls back to writing the hash inline after the
+ * filename (for compatibility with the older casefold+fscrypt format).
+ */
+static void ext4_dirdata_set(struct ext4_dir_entry_2 *de, struct inode *dir,
+			     struct ext4_dirent_fid *dfid,
+			     struct ext4_filename *fname)
+{
+	struct dx_hash_info *hinfo = &fname->hinfo;
+	unsigned int data_offset = de->name_len + 1;
+
+
+	if (dfid) {
+		unsigned int dlen = dfid->df_header.ddh_length;
+
+		if (data_offset + dlen > de->rec_len) {
+			EXT4_ERROR_INODE(dir, "Can not insert FID");
+			return;
+		}
+
+
+		de->name[de->name_len] = 0;
+		memcpy(&de->name[de->name_len + 1], dfid,
+		       dlen);
+		de->file_type |= EXT4_DIRENT_LUFID;
+		data_offset += dlen;
+	}
+
+	if (ext4_hash_in_dirent(dir)) {
+		if (ext4_has_feature_dirdata(dir->i_sb)) {
+			struct ext4_dirent_hash *dh =
+			    (struct ext4_dirent_hash *)(de->name + data_offset);
+
+			if (data_offset + sizeof(*dh) > de->rec_len) {
+				EXT4_ERROR_INODE(dir, "Can not insert dhash dirdata");
+				return;
+			}
+
+			dh->dh_header.ddh_length = sizeof(*dh);
+			dh->dh_hash.hash = cpu_to_le32(hinfo->hash);
+			dh->dh_hash.minor_hash = cpu_to_le32(hinfo->minor_hash);
+			de->file_type |= EXT4_DIRENT_CFHASH;
+		} else {
+			/* Compatibility: store hash inline after filename */
+			if (data_offset + sizeof(struct ext4_dir_entry_hash) >
+								de-> rec_len) {
+				EXT4_ERROR_INODE(dir, "Can not insert dhash");
+				return;
+			}
+
+			EXT4_DIRENT_HASHES(de)->hash = cpu_to_le32(hinfo->hash);
+			EXT4_DIRENT_HASHES(de)->minor_hash =
+						cpu_to_le32(hinfo->minor_hash);
+		}
+	}
+}
+
+
 static int dx_make_map(struct inode *dir, struct buffer_head *bh,
 		       struct dx_hash_info *hinfo,
 		       struct dx_map_entry *map_tail)
@@ -1299,9 +1450,8 @@ static int dx_make_map(struct inode *dir, struct buffer_head *bh,
 					 ((char *)de) - base))
 			return -EFSCORRUPTED;
 		if (de->name_len && de->inode) {
-			if (ext4_hash_in_dirent(dir))
-				h.hash = EXT4_DIRENT_HASH(de);
-			else {
+			if (!(ext4_dirdata_get(de, dir, NULL, &h) &
+						EXT4_DIRENT_CFHASH)) {
 				int err = ext4fs_dirhash(dir, de->name,
 						     de->name_len, &h);
 				if (err < 0)
@@ -2089,13 +2239,7 @@ void ext4_insert_dentry_data(struct inode *dir, struct inode *inode,
 	ext4_set_de_type(inode->i_sb, de, inode->i_mode);
 	de->name_len = fname_len(fname);
 	memcpy(de->name, fname_name(fname), fname_len(fname));
-	if (ext4_hash_in_dirent(dir)) {
-		struct dx_hash_info *hinfo = &fname->hinfo;
-
-		EXT4_DIRENT_HASHES(de)->hash = cpu_to_le32(hinfo->hash);
-		EXT4_DIRENT_HASHES(de)->minor_hash =
-						cpu_to_le32(hinfo->minor_hash);
-	}
+	ext4_dirdata_set(de, dir, data, fname);
 }
 
 /*
-- 
2.43.7

[PATCH v2 10/10] ext4: Add EXT4_IOC_SET_LUFID ioctl for setting LUFID on directory entries

[Artem Blagodarenko]

From: Artem Blagodarenko <artem.blagodarenko@gmail.com>

Add a new ioctl command that allows setting LUFID (Locally Unique File ID)
data on existing directory entries. This includes:

- ext4_ioctl_set_lufid(): ioctl handler that validates parameters and
  calls the underlying implementation
- ext4_set_direntry_lufid(): Core function that performs the operation by:
  * Looking up the target directory entry
  * Retrieving the associated inode
  * Deleting the old entry and re-creating it with LUFID data attached

This implementation requires the dirdata feature to be enabled on the
filesystem and properly handles transactions and inode locking to ensure
consistency.

Signed-off-by: Artem Blagodarenko artem.blagodarenko@gmail.com
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
---
 fs/ext4/ext4.h            |  15 +++++
 fs/ext4/ioctl.c           |  62 ++++++++++++++++++++
 fs/ext4/namei.c           | 120 ++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/ext4.h |  13 +++++
 4 files changed, 210 insertions(+)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index defa18d98c74..975b0975e032 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1193,6 +1193,7 @@ struct ext4_inode_info {
 #ifdef CONFIG_FS_ENCRYPTION
 	struct fscrypt_inode_info *i_crypt_info;
 #endif
+	void *i_dirdata;
 };
 
 /*
@@ -2515,6 +2516,18 @@ struct ext4_dirent_hash {
 	struct ext4_dir_entry_hash	dh_hash;
 } __packed;
 
+static inline
+struct ext4_dirent_fid *ext4_dentry_get_fid(struct super_block *sb,
+					    struct ext4_dentry_param *p)
+{
+	if (!ext4_has_feature_dirdata(sb))
+		return NULL;
+	if (p && p->edp_magic == EXT4_LUFID_MAGIC)
+		return &p->edp_dfid;
+
+	return NULL;
+}
+
 #define EXT4_FT_DIR_CSUM	0xDE
 
 /*
@@ -3215,6 +3228,8 @@ static inline int ext4_init_new_dir(handle_t *handle, struct inode *dir,
 }
 extern int ext4_dirblock_csum_verify(struct inode *inode,
 				     struct buffer_head *bh);
+extern int ext4_dirdata_set_lufid(struct inode *dir, const char *filename,
+			   int namelen, struct ext4_dentry_param *edp);
 extern int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,
 				__u32 start_minor_hash, __u32 *next_hash);
 extern int ext4_search_dir(struct buffer_head *bh,
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 1d0c3d4bdf47..9f32f21d9b3a 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -1529,6 +1529,65 @@ static int ext4_ioctl_set_tune_sb(struct file *filp,
 	return ret;
 }
 
+/*
+ * ext4_ioctl_set_lufid() - Set LUFID on a directory entry
+ * @filp:	file pointer (parent directory)
+ * @arg:	pointer to ext4_set_lufid structure with filename and LUFID data
+ *
+ * This ioctl allows setting LUFID data on an existing
+ * directory entry. It is called on the parent directory with a filename and
+ * LUFID data.
+ */
+static long ext4_ioctl_set_lufid(struct file *filp, unsigned long arg)
+{
+	struct inode *dir = file_inode(filp);
+	struct ext4_set_lufid lufid_args;
+	struct {
+		__u32 edp_magic;
+		struct ext4_dirent_data_header df_header;
+		char df_fid[255];
+	} edp;
+	int err;
+
+	/* Check if parent is a directory */
+	if (!S_ISDIR(dir->i_mode))
+		return -ENOTDIR;
+
+	/* Copy arguments from user space */
+	if (copy_from_user(&lufid_args, (struct ext4_set_lufid __user *)arg,
+			   sizeof(lufid_args)))
+		return -EFAULT;
+
+	/* Validate parameters */
+	if (lufid_args.esl_name_len == 0 || lufid_args.esl_name_len > EXT4_NAME_LEN)
+		return -EINVAL;
+
+	if (lufid_args.esl_data_len == 0 || lufid_args.esl_data_len > 255)
+		return -EINVAL;
+
+	/* Ensure filename is NUL-terminated and unmodified */
+	if (lufid_args.esl_name[lufid_args.esl_name_len - 1] != '\0')
+		return -EINVAL;
+
+	/* Prepare the dentry param struct with LUFID data */
+	edp.edp_magic = EXT4_LUFID_MAGIC;
+	edp.df_header.ddh_length = lufid_args.esl_data_len;
+	memcpy(edp.df_fid, lufid_args.esl_data, lufid_args.esl_data_len);
+
+	/* Want write access */
+	err = mnt_want_write_file(filp);
+	if (err)
+		return err;
+
+	/* Call the helper function to do the actual work */
+	err = ext4_dirdata_set_lufid(dir, lufid_args.esl_name,
+				    lufid_args.esl_name_len - 1,
+				    (struct ext4_dentry_param *)&edp);
+
+	mnt_drop_write_file(filp);
+	return err;
+}
+
 static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct inode *inode = file_inode(filp);
@@ -1912,6 +1971,8 @@ static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 					      (void __user *)arg);
 	case EXT4_IOC_SET_TUNE_SB_PARAM:
 		return ext4_ioctl_set_tune_sb(filp, (void __user *)arg);
+	case EXT4_IOC_SET_LUFID:
+		return ext4_ioctl_set_lufid(filp, arg);
 	default:
 		return -ENOTTY;
 	}
@@ -1991,6 +2052,7 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case FS_IOC_SETFSLABEL:
 	case EXT4_IOC_GETFSUUID:
 	case EXT4_IOC_SETFSUUID:
+	case EXT4_IOC_SET_LUFID:
 		break;
 	default:
 		return -ENOIOCTLCMD;
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index c799f87d7459..65c53c08213a 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2264,6 +2264,8 @@ static int add_dirent_to_buf(handle_t *handle, struct ext4_filename *fname,
 	if (ext4_has_feature_metadata_csum(inode->i_sb))
 		csum_size = sizeof(struct ext4_dir_entry_tail);
 
+	dfid = ext4_dentry_get_fid(inode->i_sb,
+		(struct ext4_dentry_param *)EXT4_I(inode)->i_dirdata);
 	if (!de) {
 		if (dfid)
 			dlen = dfid->df_header.ddh_length;
@@ -2605,6 +2607,7 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
 {
 	struct inode *dir = d_inode(dentry->d_parent);
 
+	EXT4_I(inode)->i_dirdata = dentry->d_fsdata;
 	if (fscrypt_is_nokey_name(dentry))
 		return -ENOKEY;
 	return __ext4_add_entry(handle, dir, &dentry->d_name, inode);
@@ -4361,6 +4364,123 @@ static int ext4_rename2(struct mnt_idmap *idmap,
 	return ext4_rename(idmap, old_dir, old_dentry, new_dir, new_dentry, flags);
 }
 
+/*
+ * ext4_dirdata_set_lufid() - Set LUFID data on an existing directory entry
+ * @dir:        parent directory inode
+ * @filename:   name of the file in the directory
+ * @namelen:    length of filename
+ * @edp:        pointer to initialized dentry param with LUFID data
+ *
+ * This function finds an existing directory entry, deletes it, and re-creates it
+ * with LUFID data attached. Used by the EXT4_IOC_SET_LUFID ioctl.
+ *
+ * Returns 0 on success, negative error code on failure.
+ */
+int ext4_dirdata_set_lufid(struct inode *dir, const char *filename,
+			    int namelen, struct ext4_dentry_param *edp)
+{
+	struct super_block *sb = dir->i_sb;
+	struct ext4_filename fname;
+	struct ext4_dir_entry_2 *de = NULL;
+	struct buffer_head *bh = NULL;
+	struct inode *inode = NULL;
+	handle_t *handle = NULL;
+	struct qstr d_name;
+	void *old_dirdata = NULL;
+	int err = 0;
+
+	/* Check if dirdata feature is enabled */
+	if (!ext4_has_feature_dirdata(sb))
+		return -ENOTSUPP;
+
+	if (namelen > EXT4_NAME_LEN)
+               return -ENAMETOOLONG;
+        if (namelen != strnlen(filename, namelen + 1))
+               return -EINVAL;
+
+	/* Setup the filename for lookup */
+	d_name.name = filename;
+	d_name.len = namelen;
+
+	/* Lookup the filename in the directory */
+	err = ext4_fname_setup_filename(dir, &d_name, 0, &fname);
+	if (err)
+		goto out_free;
+
+	bh = ext4_find_entry(dir, &d_name, &de, NULL);
+	if (!bh) {
+		err = -ENOENT;
+		goto out_free;
+	}
+
+	/* Get the inode number from the directory entry */
+	inode = ext4_iget(sb, le32_to_cpu(de->inode), EXT4_IGET_NORMAL);
+	if (IS_ERR(inode)) {
+		err = PTR_ERR(inode);
+		inode = NULL;
+		goto out_brelse;
+	}
+
+	/* Start a transaction */
+	handle = ext4_journal_start(dir, EXT4_HT_DIR, 
+				     2 * EXT4_DATA_TRANS_BLOCKS(sb) + 
+				     EXT4_INDEX_EXTRA_TRANS_BLOCKS);
+	if (IS_ERR(handle)) {
+		err = PTR_ERR(handle);
+		handle = NULL;
+		goto out_iput;
+	}
+
+	inode_lock(dir);
+
+	/* Delete the old entry */
+	err = ext4_delete_entry(handle, dir, de, bh);
+	if (err)
+		goto out_unlock;
+
+	brelse(bh);
+	bh = NULL;
+
+	/* Re-add the entry with LUFID data
+	 * We set i_dirdata before adding so the entry can include it
+	 */
+	old_dirdata = EXT4_I(inode)->i_dirdata;
+	EXT4_I(inode)->i_dirdata = edp;
+
+	/* Use ext4_add_entry() to properly handle hash table management
+	 * and block splitting, just like rename does. This ensures the entry
+	 * is placed in the correct hash block and avoids breaking dirhash.
+	 */
+	{
+		struct dentry parent_dentry = { .d_inode = dir };
+		struct dentry new_dentry = {
+			.d_name = d_name,
+			.d_parent = &parent_dentry,
+			.d_inode = inode,  /* Same inode (in-place update) */
+			.d_fsdata = edp,   /* required */
+		};
+		err = ext4_add_entry(handle, &new_dentry, inode);
+	}
+	EXT4_I(inode)->i_dirdata = old_dirdata;
+
+	/* Update inode times */
+	inode_set_ctime_current(dir);
+	inode_inc_iversion(dir);
+	ext4_mark_inode_dirty(handle, dir);
+
+out_unlock:
+	inode_unlock(dir);
+	ext4_journal_stop(handle);
+out_iput:
+	iput(inode);
+out_brelse:
+	brelse(bh);
+out_free:
+	ext4_fname_free_filename(&fname);
+
+	return err;
+}
+
 /*
  * directories can handle most operations...
  */
diff --git a/include/uapi/linux/ext4.h b/include/uapi/linux/ext4.h
index 9c683991c32f..b04bbb2818a3 100644
--- a/include/uapi/linux/ext4.h
+++ b/include/uapi/linux/ext4.h
@@ -35,6 +35,7 @@
 #define EXT4_IOC_SETFSUUID		_IOW('f', 44, struct fsuuid)
 #define EXT4_IOC_GET_TUNE_SB_PARAM	_IOR('f', 45, struct ext4_tune_sb_params)
 #define EXT4_IOC_SET_TUNE_SB_PARAM	_IOW('f', 46, struct ext4_tune_sb_params)
+#define EXT4_IOC_SET_LUFID		_IOW('f', 47, struct ext4_set_lufid)
 
 #define EXT4_IOC_SHUTDOWN _IOR('X', 125, __u32)
 
@@ -92,6 +93,18 @@ struct move_extent {
 	__u64 moved_len;	/* moved block length */
 };
 
+/*
+ * Structure for EXT4_IOC_SET_LUFID
+ * Sets LUFID on a directory entry
+ * Called on parent directory with filename and LUFID data as arguments
+ */
+struct ext4_set_lufid {
+	__u8 esl_name_len;	/* length of filename */
+	__u8 esl_data_len;	/* length of LUFID data */
+	char  esl_name[255 + 1]; /* filename (NUL-terminated) */
+	char  esl_data[255 + 1]; /* LUFID data (raw bytes) */
+};
+
 /*
  * Flags used by EXT4_IOC_SHUTDOWN
  */
-- 
2.43.7

[syzbot ci] Re: Data in direntry (dirdata) feature

[syzbot ci]

syzbot ci has tested the following series

[v2] Data in direntry (dirdata) feature
https://lore.kernel.org/all/20260610152417.13576-1-ablagodarenko@thelustrecollective.com
* [PATCH v2 01/10] ext4: replace ext4_dir_entry with ext4_dir_entry_2
* [PATCH v2 02/10] ext4: add ext4_dir_entry_is_tail()
* [PATCH v2 03/10] ext4: refactor dx_root to support variable dirent sizes
* [PATCH v2 04/10] ext4: add dirdata format definitions and access helpers
* [PATCH v2 05/10] ext4: preserve dirdata bits in get_dtype()
* [PATCH v2 06/10] ext4: add ext4_dir_entry_len() and harden dirdata parsing
* [PATCH v2 07/10] ext4: rename ext4_dir_rec_len() and clarify dirdata usage
* [PATCH v2 08/10] ext4: dirdata feature
* [PATCH v2 09/10] ext4: add dirdata set/get helpers
* [PATCH v2 10/10] ext4: Add EXT4_IOC_SET_LUFID ioctl for setting LUFID on directory entries

and found the following issues:
* KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
* KASAN: slab-out-of-bounds Read in ext4_inlinedir_to_tree
* KASAN: slab-use-after-free Read in __ext4_check_dir_entry
* KASAN: slab-use-after-free Read in ext4_inlinedir_to_tree
* KASAN: use-after-free Read in __ext4_check_dir_entry

Full report is available here:
https://ci.syzbot.org/series/5bf0e2fa-2e68-4532-8396-4568879b2788

***

KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
syz repro: https://ci.syzbot.org/findings/b0854918-13f9-49dd-ab30-12154f0debe2/syz_repro

loop0: lost filesystem error report for type 5 error -117
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
Read of size 1 at addr ffff8881022db7f5 by task syz.0.23/5815

CPU: 1 UID: 0 PID: 5815 Comm: syz.0.23 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
 __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
 ext4_check_all_de+0x66/0x150 fs/ext4/dir.c:657
 ext4_convert_inline_data_nolock+0x1b7/0x990 fs/ext4/inline.c:1121
 ext4_try_add_inline_entry+0x604/0x8e0 fs/ext4/inline.c:1247
 __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
 ext4_add_entry fs/ext4/namei.c:2613 [inline]
 ext4_mkdir+0x5e5/0xce0 fs/ext4/namei.c:3175
 vfs_mkdir+0x413/0x630 fs/namei.c:5271
 filename_mkdirat+0x285/0x510 fs/namei.c:5304
 __do_sys_mkdirat fs/namei.c:5325 [inline]
 __se_sys_mkdirat+0x35/0x150 fs/namei.c:5322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f669359bcc7
Code: 00 66 90 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 db f7 ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 b8 02 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd42381d38 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007ffd42381dc0 RCX: 00007f669359bcc7
RDX: 00000000000001ff RSI: 0000200000001200 RDI: 00000000ffffff9c
RBP: 00002000000024c0 R08: 0000200000000240 R09: 0000000000000000
R10: 00002000000024c0 R11: 0000000000000246 R12: 0000200000001200
R13: 00007ffd42381d80 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 5066:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5420
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 kernfs_get_open_node fs/kernfs/file.c:543 [inline]
 kernfs_fop_open+0x862/0xda0 fs/kernfs/file.c:718
 do_dentry_open+0x822/0x13a0 fs/open.c:947
 vfs_open+0x3b/0x340 fs/open.c:1079
 do_open fs/namei.c:4699 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4858
 do_file_open+0x23e/0x4a0 fs/namei.c:4887
 do_sys_openat2+0x113/0x200 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 kvfree_call_rcu+0x100/0x430 mm/slab_common.c:1970
 kernfs_unlink_open_file+0x3fe/0x4b0 fs/kernfs/file.c:604
 kernfs_fop_release+0x2eb/0x440 fs/kernfs/file.c:783
 __fput+0x44f/0xa60 fs/file_table.c:510
 fput_close_sync+0x11f/0x240 fs/file_table.c:615
 __do_sys_close fs/open.c:1507 [inline]
 __se_sys_close fs/open.c:1492 [inline]
 __x64_sys_close+0x7e/0x110 fs/open.c:1492
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8881022db700
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 117 bytes to the right of
 allocated 128-byte region [ffff8881022db700, ffff8881022db780)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1022db
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000000 ffff888100041a00 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2000(__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 0, tgid 0 (swapper/0), ts 2408938923, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x339/0x3d0 mm/slub.c:7272
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
 alloc_from_pcs mm/slub.c:4750 [inline]
 slab_alloc_node mm/slub.c:4884 [inline]
 __do_kmalloc_node mm/slub.c:5295 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 __alloc_empty_sheaf mm/slub.c:2768 [inline]
 alloc_empty_sheaf mm/slub.c:2783 [inline]
 __pcs_replace_empty_main+0x2df/0x720 mm/slub.c:4647
 alloc_from_pcs mm/slub.c:4750 [inline]
 slab_alloc_node mm/slub.c:4884 [inline]
 kmem_cache_alloc_noprof+0x37d/0x650 mm/slub.c:4906
 dup_fd+0x55/0xb40 fs/file.c:390
 copy_files+0xc8/0x120 kernel/fork.c:1639
 copy_process+0x1d94/0x4440 kernel/fork.c:2252
 kernel_clone+0x2d7/0x940 kernel/fork.c:2722
 user_mode_thread+0x110/0x180 kernel/fork.c:2798
 rest_init+0x23/0x300 init/main.c:727
 start_kernel+0x38a/0x3e0 init/main.c:1220
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881022db680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881022db700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881022db780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                             ^
 ffff8881022db800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881022db880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: slab-out-of-bounds Read in ext4_inlinedir_to_tree

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
syz repro: https://ci.syzbot.org/findings/2dff870b-f382-4c93-8d8d-b2291d921224/syz_repro

loop1: lost filesystem error report for type 5 error -117
EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4095 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_inlinedir_to_tree+0xda5/0x10d0 fs/ext4/inline.c:1335
Read of size 2 at addr ffff888115a3183c by task syz.1.18/5839

CPU: 1 UID: 0 PID: 5839 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dir_entry_len fs/ext4/ext4.h:4095 [inline]
 ext4_inlinedir_to_tree+0xda5/0x10d0 fs/ext4/inline.c:1335
 ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
 iterate_dir+0x399/0x570 fs/readdir.c:110
 __do_sys_getdents64 fs/readdir.c:399 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3e02b9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3e03ad5028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f3e02e15fa0 RCX: 00007f3e02b9ce59
RDX: 0000000000001000 RSI: 0000200000000f80 RDI: 0000000000000004
RBP: 00007f3e02c32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3e02e16038 R14: 00007f3e02e15fa0 R15: 00007ffcaa902298
 </TASK>

Allocated by task 5839:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5296 [inline]
 __kmalloc_noprof+0x35c/0x760 mm/slub.c:5308
 kmalloc_noprof include/linux/slab.h:954 [inline]
 ext4_inlinedir_to_tree+0x312/0x10d0 fs/ext4/inline.c:1292
 ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
 iterate_dir+0x399/0x570 fs/readdir.c:110
 __do_sys_getdents64 fs/readdir.c:399 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888115a31800
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes to the right of
 allocated 60-byte region [ffff888115a31800, ffff888115a3183c)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x115a31
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5051, tgid 5051 (acpid), ts 27203740677, free_ts 27201732767
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x339/0x3d0 mm/slub.c:7272
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
 alloc_from_pcs mm/slub.c:4750 [inline]
 slab_alloc_node mm/slub.c:4884 [inline]
 __do_kmalloc_node mm/slub.c:5295 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 tomoyo_get_name+0x20c/0x590 security/tomoyo/memory.c:173
 tomoyo_parse_name_union+0xd9/0x130 security/tomoyo/util.c:260
 tomoyo_update_path_acl security/tomoyo/file.c:399 [inline]
 tomoyo_write_file+0x3a6/0xc50 security/tomoyo/file.c:1027
 tomoyo_write_domain2 security/tomoyo/common.c:1160 [inline]
 tomoyo_add_entry security/tomoyo/common.c:2177 [inline]
 tomoyo_supervisor+0x1208/0x1570 security/tomoyo/common.c:2238
 tomoyo_audit_path_log security/tomoyo/file.c:169 [inline]
 tomoyo_path_permission+0x25a/0x380 security/tomoyo/file.c:592
 tomoyo_check_open_permission+0x2b2/0x470 security/tomoyo/file.c:782
 security_file_open+0xa9/0x240 security/security.c:2739
 do_dentry_open+0x4a8/0x13a0 fs/open.c:924
 vfs_open+0x3b/0x340 fs/open.c:1079
page last free pid 15 tgid 15 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1397 [inline]
 __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
 __tlb_remove_table_free mm/mmu_gather.c:228 [inline]
 tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:291
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
 handle_softirqs+0x22a/0x840 kernel/softirq.c:622
 run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 kthread+0x389/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888115a31700: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888115a31780: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
>ffff888115a31800: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
                                        ^
 ffff888115a31880: 00 00 00 00 00 00 02 fc fc fc fc fc fc fc fc fc
 ffff888115a31900: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: slab-use-after-free Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
syz repro: https://ci.syzbot.org/findings/f1d48ea1-6e87-4d64-9c13-8bf8aed109fc/syz_repro

loop0: lost filesystem error report for type 5 error -117
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
BUG: KASAN: slab-use-after-free in __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
Read of size 1 at addr ffff888114d8c045 by task syz.0.20/5821

CPU: 1 UID: 0 PID: 5821 Comm: syz.0.20 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
 __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
 ext4_find_dest_de+0x136/0x770 fs/ext4/namei.c:2203
 ext4_add_dirent_to_inline+0xcf/0x430 fs/ext4/inline.c:984
 ext4_try_add_inline_entry+0x235/0x8e0 fs/ext4/inline.c:1213
 __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
 ext4_add_entry fs/ext4/namei.c:2613 [inline]
 ext4_add_nondir+0x111/0x310 fs/ext4/namei.c:2936
 ext4_create+0x2e9/0x470 fs/ext4/namei.c:2982
 lookup_open fs/namei.c:4511 [inline]
 open_last_lookups fs/namei.c:4611 [inline]
 path_openat+0x1395/0x3860 fs/namei.c:4855
 do_file_open+0x23e/0x4a0 fs/namei.c:4887
 do_sys_openat2+0x113/0x200 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f922219ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9223137028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f9222415fa0 RCX: 00007f922219ce59
RDX: 0000000000042042 RSI: 0000200000000080 RDI: 0000000000000004
RBP: 00007f9222232d6f R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000014a R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9222416038 R14: 00007f9222415fa0 R15: 00007ffd01a2d448
 </TASK>

Allocated by task 5484:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4570 [inline]
 slab_alloc_node mm/slub.c:4899 [inline]
 kmem_cache_alloc_node_noprof+0x384/0x690 mm/slub.c:4951
 kmalloc_reserve net/core/skbuff.c:613 [inline]
 __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
 alloc_skb include/linux/skbuff.h:1385 [inline]
 nlmsg_new include/net/netlink.h:1055 [inline]
 mpls_netconf_notify_devconf+0x46/0x100 net/mpls/af_mpls.c:1217
 mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
 notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
 call_netdevice_notifiers net/core/dev.c:2301 [inline]
 unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
 ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
 ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
 cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
 kthread+0x389/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 5484:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2689 [inline]
 slab_free mm/slub.c:6251 [inline]
 kfree+0x1c5/0x640 mm/slub.c:6566
 skb_kfree_head net/core/skbuff.c:1075 [inline]
 skb_free_head net/core/skbuff.c:1087 [inline]
 skb_release_data+0x828/0xa60 net/core/skbuff.c:1114
 skb_release_all net/core/skbuff.c:1189 [inline]
 __kfree_skb+0x5d/0x210 net/core/skbuff.c:1203
 netlink_broadcast_filtered+0xe18/0xf20 net/netlink/af_netlink.c:1540
 nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
 nlmsg_multicast include/net/netlink.h:1184 [inline]
 nlmsg_notify+0xf0/0x1a0 net/netlink/af_netlink.c:2598
 mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
 notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
 call_netdevice_notifiers net/core/dev.c:2301 [inline]
 unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
 ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
 ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
 cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
 kthread+0x389/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888114d8c000
 which belongs to the cache skbuff_small_head of size 704
The buggy address is located 69 bytes inside of
 freed 704-byte region [ffff888114d8c000, ffff888114d8c2c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x114d8c
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000040 ffff888160416b40 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800120012 00000000f5000000 0000000000000000
head: 017ff00000000040 ffff888160416b40 dead000000000100 dead000000000122
head: 0000000000000000 0000000800120012 00000000f5000000 0000000000000000
head: 017ff00000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5484, tgid 5484 (kworker/u8:2), ts 72573003529, free_ts 72546506446
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x339/0x3d0 mm/slub.c:7272
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
 alloc_from_pcs mm/slub.c:4750 [inline]
 slab_alloc_node mm/slub.c:4884 [inline]
 kmem_cache_alloc_node_noprof+0x441/0x690 mm/slub.c:4951
 kmalloc_reserve net/core/skbuff.c:613 [inline]
 __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
 alloc_skb include/linux/skbuff.h:1385 [inline]
 nlmsg_new include/net/netlink.h:1055 [inline]
 mpls_netconf_notify_devconf+0x46/0x100 net/mpls/af_mpls.c:1217
 mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
 notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
 call_netdevice_notifiers net/core/dev.c:2301 [inline]
 unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
 ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
 ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
 cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
page last free pid 5484 tgid 5484 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1397 [inline]
 __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
 stack_depot_save_flags+0x40e/0x810 lib/stackdepot.c:735
 kasan_save_stack mm/kasan/common.c:58 [inline]
 kasan_save_track+0x4f/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4570 [inline]
 slab_alloc_node mm/slub.c:4899 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4906
 kmem_alloc_batch lib/debugobjects.c:371 [inline]
 fill_pool+0x156/0x580 lib/debugobjects.c:420
 debug_objects_fill_pool lib/debugobjects.c:752 [inline]
 debug_object_activate+0x4a3/0x580 lib/debugobjects.c:841
 debug_rcu_head_queue kernel/rcu/rcu.h:236 [inline]
 __call_rcu_common kernel/rcu/tree.c:3116 [inline]
 call_rcu+0x43/0x890 kernel/rcu/tree.c:3251
 kernfs_put+0x259/0x520 fs/kernfs/dir.c:618
 kernfs_remove_by_name_ns+0xc8/0x140 fs/kernfs/dir.c:1799
 device_remove_class_symlinks+0x178/0x190 drivers/base/core.c:3479
 device_del+0x400/0x8f0 drivers/base/core.c:3881
 unregister_netdevice_many_notify+0x1d5f/0x22c0 net/core/dev.c:12456
 ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
 ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
 cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397

Memory state around the buggy address:
 ffff888114d8bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888114d8bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888114d8c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888114d8c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888114d8c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


***

KASAN: slab-use-after-free Read in ext4_inlinedir_to_tree

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
syz repro: https://ci.syzbot.org/findings/f42da242-e16e-4f10-bf25-0bd7e192d989/syz_repro

loop0: lost filesystem error report for type 5 error -117
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
BUG: KASAN: slab-use-after-free in ext4_inlinedir_to_tree+0x94c/0x10d0 fs/ext4/inline.c:1335
Read of size 1 at addr ffff88816fee8825 by task syz.0.20/5867

CPU: 1 UID: 0 PID: 5867 Comm: syz.0.20 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
 ext4_inlinedir_to_tree+0x94c/0x10d0 fs/ext4/inline.c:1335
 ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
 iterate_dir+0x399/0x570 fs/readdir.c:110
 __do_sys_getdents fs/readdir.c:319 [inline]
 __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f010ad9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f010bc0f028 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007f010b015fa0 RCX: 00007f010ad9ce59
RDX: 0000000000000054 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f010ae32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f010b016038 R14: 00007f010b015fa0 R15: 00007ffd93577348
 </TASK>

Allocated by task 5064:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5296 [inline]
 __kmalloc_noprof+0x35c/0x760 mm/slub.c:5308
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
 tomoyo_encode+0x28b/0x550 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x58d/0x5d0 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
 security_inode_getattr+0x12b/0x310 security/security.c:1895
 vfs_getattr fs/stat.c:259 [inline]
 vfs_fstat fs/stat.c:281 [inline]
 vfs_fstatat+0xb4/0x170 fs/stat.c:371
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat fs/stat.c:532 [inline]
 __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5064:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2689 [inline]
 slab_free mm/slub.c:6251 [inline]
 kfree+0x1c5/0x640 mm/slub.c:6566
 tomoyo_path_perm+0x403/0x560 security/tomoyo/file.c:847
 security_inode_getattr+0x12b/0x310 security/security.c:1895
 vfs_getattr fs/stat.c:259 [inline]
 vfs_fstat fs/stat.c:281 [inline]
 vfs_fstatat+0xb4/0x170 fs/stat.c:371
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat fs/stat.c:532 [inline]
 __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88816fee8800
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 37 bytes inside of
 freed 64-byte region [ffff88816fee8800, ffff88816fee8840)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16fee8
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 21294026082, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x339/0x3d0 mm/slub.c:7272
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
 alloc_from_pcs mm/slub.c:4750 [inline]
 slab_alloc_node mm/slub.c:4884 [inline]
 __do_kmalloc_node mm/slub.c:5295 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 handler_new_ref+0x261/0x9c0 drivers/media/v4l2-core/v4l2-ctrls-core.c:1882
 v4l2_ctrl_add_handler+0x19f/0x290 drivers/media/v4l2-core/v4l2-ctrls-core.c:2443
 vivid_create_controls+0x332d/0x3bd0 drivers/media/test-drivers/vivid/vivid-ctrls.c:2072
 vivid_create_instance drivers/media/test-drivers/vivid/vivid-core.c:1933 [inline]
 vivid_probe+0x4261/0x72b0 drivers/media/test-drivers/vivid/vivid-core.c:2095
 platform_probe+0xf9/0x190 drivers/base/platform.c:1432
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x267/0xaf0 drivers/base/dd.c:709
 __driver_probe_device+0x1ef/0x380 drivers/base/dd.c:871
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:901
 __driver_attach+0x34c/0x640 drivers/base/dd.c:1295
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88816fee8700: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
 ffff88816fee8780: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff88816fee8800: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                               ^
 ffff88816fee8880: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88816fee8900: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: use-after-free Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
syz repro: https://ci.syzbot.org/findings/57c0b75a-8922-4dc1-9a20-ca947564792b/syz_repro

==================================================================
BUG: KASAN: use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
BUG: KASAN: use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
Read of size 1 at addr ffff88816be85045 by task syz.2.21/5880

CPU: 1 UID: 0 PID: 5880 Comm: syz.2.21 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
 __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
 ext4_find_dest_de+0x136/0x770 fs/ext4/namei.c:2203
 ext4_add_dirent_to_inline+0xcf/0x430 fs/ext4/inline.c:984
 ext4_try_add_inline_entry+0x235/0x8e0 fs/ext4/inline.c:1213
 __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
 ext4_add_entry fs/ext4/namei.c:2613 [inline]
 ext4_add_nondir+0x111/0x310 fs/ext4/namei.c:2936
 ext4_create+0x2e9/0x470 fs/ext4/namei.c:2982
 lookup_open fs/namei.c:4511 [inline]
 open_last_lookups fs/namei.c:4611 [inline]
 path_openat+0x1395/0x3860 fs/namei.c:4855
 do_file_open+0x23e/0x4a0 fs/namei.c:4887
 do_sys_openat2+0x113/0x200 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5713b9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff672b25f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f5713e15fa0 RCX: 00007f5713b9ce59
RDX: 0000000000042042 RSI: 0000200000000080 RDI: 0000000000000004
RBP: 00007f5713c32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000014a R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5713e15fac R14: 00007f5713e15fa0 R15: 00007f5713e15fa0
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16be85
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 057ff00000000000 ffffea0005afa0c8 ffffea0005afa1c8 0000000000000000
raw: 0000000000000000 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xcc0(GFP_KERNEL), pid 5630, tgid 5630 (syz-executor), ts 67290853657, free_ts 69321168948
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 __alloc_pages_noprof+0x10/0x100 mm/page_alloc.c:5255
 alloc_pages_bulk_noprof+0x5ff/0x7c0 mm/page_alloc.c:5175
 ___alloc_pages_bulk mm/kasan/shadow.c:345 [inline]
 __kasan_populate_vmalloc_do mm/kasan/shadow.c:370 [inline]
 __kasan_populate_vmalloc+0xc1/0x1d0 mm/kasan/shadow.c:424
 kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
 alloc_vmap_area+0xd47/0x1480 mm/vmalloc.c:2123
 __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3226
 __vmalloc_node_range_noprof+0x36a/0x1750 mm/vmalloc.c:4024
 vmalloc_user_noprof+0xad/0xe0 mm/vmalloc.c:4218
 kcov_ioctl+0x55/0x620 kernel/kcov.c:726
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5693 tgid 5693 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1397 [inline]
 __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
 kasan_depopulate_vmalloc_pte+0x6d/0x90 mm/kasan/shadow.c:484
 apply_to_pte_range mm/memory.c:3338 [inline]
 apply_to_pmd_range mm/memory.c:3382 [inline]
 apply_to_pud_range mm/memory.c:3418 [inline]
 apply_to_p4d_range mm/memory.c:3454 [inline]
 __apply_to_page_range+0xbdc/0x1420 mm/memory.c:3490
 __kasan_release_vmalloc+0xa2/0xd0 mm/kasan/shadow.c:602
 kasan_release_vmalloc include/linux/kasan.h:593 [inline]
 kasan_release_vmalloc_node mm/vmalloc.c:2284 [inline]
 purge_vmap_node+0x220/0x960 mm/vmalloc.c:2306
 __purge_vmap_area_lazy+0x779/0xb40 mm/vmalloc.c:2396
 drain_vmap_area_work+0x27/0x40 mm/vmalloc.c:2430
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
 kthread+0x389/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff88816be84f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88816be84f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88816be85000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff88816be85080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88816be85100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@syzkaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.

To test a patch for this bug, please reply with `#syz test`
(should be on a separate line).

The patch should be attached to the email.
Note: arguments like custom git repos and branches are not supported.

Re: [syzbot ci] Re: Data in direntry (dirdata) feature

[Artem Blagodarenko]

[-- Attachment #1.1: Type: text/plain, Size: 43669 bytes --]

Thanks for the report. The attached patch addresses the issues found in
the dirdata series review (dx_get_dx_info/get_dx_countlimit blocksize
fallback, dfid parameter shadowing in ext4_dirdata_get, and the unsafe
delete-before-add in EXT4_IOC_SET_LUFID).


#syz test

On Thu, Jun 11, 2026 11:29 AM, syzbot ci <
syzbot+cid7b922cb3d448114@syzkaller.appspotmail.com> wrote:

> syzbot ci has tested the following series
>
> [v2] Data in direntry (dirdata) feature
>
> https://lore.kernel.org/all/20260610152417.13576-1-ablagodarenko@thelustrecollective.com
> * [PATCH v2 01/10] ext4: replace ext4_dir_entry with ext4_dir_entry_2
> * [PATCH v2 02/10] ext4: add ext4_dir_entry_is_tail()
> * [PATCH v2 03/10] ext4: refactor dx_root to support variable dirent sizes
> * [PATCH v2 04/10] ext4: add dirdata format definitions and access helpers
> * [PATCH v2 05/10] ext4: preserve dirdata bits in get_dtype()
> * [PATCH v2 06/10] ext4: add ext4_dir_entry_len() and harden dirdata
> parsing
> * [PATCH v2 07/10] ext4: rename ext4_dir_rec_len() and clarify dirdata
> usage
> * [PATCH v2 08/10] ext4: dirdata feature
> * [PATCH v2 09/10] ext4: add dirdata set/get helpers
> * [PATCH v2 10/10] ext4: Add EXT4_IOC_SET_LUFID ioctl for setting LUFID on
> directory entries
>
> and found the following issues:
> * KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
> * KASAN: slab-out-of-bounds Read in ext4_inlinedir_to_tree
> * KASAN: slab-use-after-free Read in __ext4_check_dir_entry
> * KASAN: slab-use-after-free Read in ext4_inlinedir_to_tree
> * KASAN: use-after-free Read in __ext4_check_dir_entry
>
> Full report is available here:
> https://ci.syzbot.org/series/5bf0e2fa-2e68-4532-8396-4568879b2788
>
> ***
>
> KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
>
> tree:      torvalds
> URL:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
> arch:      amd64
> compiler:  Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:
> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
> syz repro:
> https://ci.syzbot.org/findings/b0854918-13f9-49dd-ab30-12154f0debe2/syz_repro
>
> loop0: lost filesystem error report for type 5 error -117
> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000
> r/w without journal. Quota mode: none.
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in ext4_dirent_get_data_len
> fs/ext4/ext4.h:4069 [inline]
> BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4096
> [inline]
> BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x65a/0xc40
> fs/ext4/dir.c:96
> Read of size 1 at addr ffff8881022db7f5 by task syz.0.23/5815
>
> CPU: 1 UID: 0 PID: 5815 Comm: syz.0.23 Not tainted syzkaller #0
> PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>  __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
>  ext4_check_all_de+0x66/0x150 fs/ext4/dir.c:657
>  ext4_convert_inline_data_nolock+0x1b7/0x990 fs/ext4/inline.c:1121
>  ext4_try_add_inline_entry+0x604/0x8e0 fs/ext4/inline.c:1247
>  __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
>  ext4_add_entry fs/ext4/namei.c:2613 [inline]
>  ext4_mkdir+0x5e5/0xce0 fs/ext4/namei.c:3175
>  vfs_mkdir+0x413/0x630 fs/namei.c:5271
>  filename_mkdirat+0x285/0x510 fs/namei.c:5304
>  __do_sys_mkdirat fs/namei.c:5325 [inline]
>  __se_sys_mkdirat+0x35/0x150 fs/namei.c:5322
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f669359bcc7
> Code: 00 66 90 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 db f7 ff
> ff 66 2e 0f 1f 84 00 00 00 00 00 90 b8 02 01 00 00 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffd42381d38 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
> RAX: ffffffffffffffda RBX: 00007ffd42381dc0 RCX: 00007f669359bcc7
> RDX: 00000000000001ff RSI: 0000200000001200 RDI: 00000000ffffff9c
> RBP: 00002000000024c0 R08: 0000200000000240 R09: 0000000000000000
> R10: 00002000000024c0 R11: 0000000000000246 R12: 0000200000001200
> R13: 00007ffd42381d80 R14: 0000000000000000 R15: 0000000000000000
>  </TASK>
>
> Allocated by task 5066:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>  __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5420
>  kmalloc_noprof include/linux/slab.h:950 [inline]
>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>  kernfs_get_open_node fs/kernfs/file.c:543 [inline]
>  kernfs_fop_open+0x862/0xda0 fs/kernfs/file.c:718
>  do_dentry_open+0x822/0x13a0 fs/open.c:947
>  vfs_open+0x3b/0x340 fs/open.c:1079
>  do_open fs/namei.c:4699 [inline]
>  path_openat+0x2e08/0x3860 fs/namei.c:4858
>  do_file_open+0x23e/0x4a0 fs/namei.c:4887
>  do_sys_openat2+0x113/0x200 fs/open.c:1364
>  do_sys_open fs/open.c:1370 [inline]
>  __do_sys_openat fs/open.c:1386 [inline]
>  __se_sys_openat fs/open.c:1381 [inline]
>  __x64_sys_openat+0x138/0x170 fs/open.c:1381
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Last potentially related work creation:
>  kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
>  kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
>  kvfree_call_rcu+0x100/0x430 mm/slab_common.c:1970
>  kernfs_unlink_open_file+0x3fe/0x4b0 fs/kernfs/file.c:604
>  kernfs_fop_release+0x2eb/0x440 fs/kernfs/file.c:783
>  __fput+0x44f/0xa60 fs/file_table.c:510
>  fput_close_sync+0x11f/0x240 fs/file_table.c:615
>  __do_sys_close fs/open.c:1507 [inline]
>  __se_sys_close fs/open.c:1492 [inline]
>  __x64_sys_close+0x7e/0x110 fs/open.c:1492
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> The buggy address belongs to the object at ffff8881022db700
>  which belongs to the cache kmalloc-128 of size 128
> The buggy address is located 117 bytes to the right of
>  allocated 128-byte region [ffff8881022db700, ffff8881022db780)
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1022db
> flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
> page_type: f5(slab)
> raw: 017ff00000000000 ffff888100041a00 dead000000000100 dead000000000122
> raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 0, migratetype Unmovable, gfp_mask
> 0xd2000(__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 0,
> tgid 0 (swapper/0), ts 2408938923, free_ts 0
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>  prep_new_page mm/page_alloc.c:1861 [inline]
>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>  alloc_slab_page mm/slub.c:3278 [inline]
>  allocate_slab+0x77/0x660 mm/slub.c:3467
>  new_slab mm/slub.c:3525 [inline]
>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>  refill_sheaf mm/slub.c:2816 [inline]
>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>  alloc_from_pcs mm/slub.c:4750 [inline]
>  slab_alloc_node mm/slub.c:4884 [inline]
>  __do_kmalloc_node mm/slub.c:5295 [inline]
>  __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
>  kmalloc_noprof include/linux/slab.h:954 [inline]
>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>  __alloc_empty_sheaf mm/slub.c:2768 [inline]
>  alloc_empty_sheaf mm/slub.c:2783 [inline]
>  __pcs_replace_empty_main+0x2df/0x720 mm/slub.c:4647
>  alloc_from_pcs mm/slub.c:4750 [inline]
>  slab_alloc_node mm/slub.c:4884 [inline]
>  kmem_cache_alloc_noprof+0x37d/0x650 mm/slub.c:4906
>  dup_fd+0x55/0xb40 fs/file.c:390
>  copy_files+0xc8/0x120 kernel/fork.c:1639
>  copy_process+0x1d94/0x4440 kernel/fork.c:2252
>  kernel_clone+0x2d7/0x940 kernel/fork.c:2722
>  user_mode_thread+0x110/0x180 kernel/fork.c:2798
>  rest_init+0x23/0x300 init/main.c:727
>  start_kernel+0x38a/0x3e0 init/main.c:1220
> page_owner free stack trace missing
>
> Memory state around the buggy address:
>  ffff8881022db680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff8881022db700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffff8881022db780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>                                                              ^
>  ffff8881022db800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff8881022db880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ==================================================================
>
>
> ***
>
> KASAN: slab-out-of-bounds Read in ext4_inlinedir_to_tree
>
> tree:      torvalds
> URL:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
> arch:      amd64
> compiler:  Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:
> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
> syz repro:
> https://ci.syzbot.org/findings/2dff870b-f382-4c93-8d8d-b2291d921224/syz_repro
>
> loop1: lost filesystem error report for type 5 error -117
> EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000
> r/w without journal. Quota mode: none.
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4095
> [inline]
> BUG: KASAN: slab-out-of-bounds in ext4_inlinedir_to_tree+0xda5/0x10d0
> fs/ext4/inline.c:1335
> Read of size 2 at addr ffff888115a3183c by task syz.1.18/5839
>
> CPU: 1 UID: 0 PID: 5839 Comm: syz.1.18 Not tainted syzkaller #0
> PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  ext4_dir_entry_len fs/ext4/ext4.h:4095 [inline]
>  ext4_inlinedir_to_tree+0xda5/0x10d0 fs/ext4/inline.c:1335
>  ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
>  ext4_dx_readdir fs/ext4/dir.c:600 [inline]
>  ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
>  iterate_dir+0x399/0x570 fs/readdir.c:110
>  __do_sys_getdents64 fs/readdir.c:399 [inline]
>  __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f3e02b9ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f3e03ad5028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
> RAX: ffffffffffffffda RBX: 00007f3e02e15fa0 RCX: 00007f3e02b9ce59
> RDX: 0000000000001000 RSI: 0000200000000f80 RDI: 0000000000000004
> RBP: 00007f3e02c32d6f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f3e02e16038 R14: 00007f3e02e15fa0 R15: 00007ffcaa902298
>  </TASK>
>
> Allocated by task 5839:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>  __do_kmalloc_node mm/slub.c:5296 [inline]
>  __kmalloc_noprof+0x35c/0x760 mm/slub.c:5308
>  kmalloc_noprof include/linux/slab.h:954 [inline]
>  ext4_inlinedir_to_tree+0x312/0x10d0 fs/ext4/inline.c:1292
>  ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
>  ext4_dx_readdir fs/ext4/dir.c:600 [inline]
>  ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
>  iterate_dir+0x399/0x570 fs/readdir.c:110
>  __do_sys_getdents64 fs/readdir.c:399 [inline]
>  __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> The buggy address belongs to the object at ffff888115a31800
>  which belongs to the cache kmalloc-64 of size 64
> The buggy address is located 0 bytes to the right of
>  allocated 60-byte region [ffff888115a31800, ffff888115a3183c)
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x115a31
> flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
> page_type: f5(slab)
> raw: 017ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
> raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 0, migratetype Unmovable, gfp_mask
> 0xd2c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
> pid 5051, tgid 5051 (acpid), ts 27203740677, free_ts 27201732767
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>  prep_new_page mm/page_alloc.c:1861 [inline]
>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>  alloc_slab_page mm/slub.c:3278 [inline]
>  allocate_slab+0x77/0x660 mm/slub.c:3467
>  new_slab mm/slub.c:3525 [inline]
>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>  refill_sheaf mm/slub.c:2816 [inline]
>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>  alloc_from_pcs mm/slub.c:4750 [inline]
>  slab_alloc_node mm/slub.c:4884 [inline]
>  __do_kmalloc_node mm/slub.c:5295 [inline]
>  __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
>  kmalloc_noprof include/linux/slab.h:954 [inline]
>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>  tomoyo_get_name+0x20c/0x590 security/tomoyo/memory.c:173
>  tomoyo_parse_name_union+0xd9/0x130 security/tomoyo/util.c:260
>  tomoyo_update_path_acl security/tomoyo/file.c:399 [inline]
>  tomoyo_write_file+0x3a6/0xc50 security/tomoyo/file.c:1027
>  tomoyo_write_domain2 security/tomoyo/common.c:1160 [inline]
>  tomoyo_add_entry security/tomoyo/common.c:2177 [inline]
>  tomoyo_supervisor+0x1208/0x1570 security/tomoyo/common.c:2238
>  tomoyo_audit_path_log security/tomoyo/file.c:169 [inline]
>  tomoyo_path_permission+0x25a/0x380 security/tomoyo/file.c:592
>  tomoyo_check_open_permission+0x2b2/0x470 security/tomoyo/file.c:782
>  security_file_open+0xa9/0x240 security/security.c:2739
>  do_dentry_open+0x4a8/0x13a0 fs/open.c:924
>  vfs_open+0x3b/0x340 fs/open.c:1079
> page last free pid 15 tgid 15 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  __free_pages_prepare mm/page_alloc.c:1397 [inline]
>  __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
>  __tlb_remove_table_free mm/mmu_gather.c:228 [inline]
>  tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:291
>  rcu_do_batch kernel/rcu/tree.c:2617 [inline]
>  rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
>  handle_softirqs+0x22a/0x840 kernel/softirq.c:622
>  run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
>  smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>
> Memory state around the buggy address:
>  ffff888115a31700: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>  ffff888115a31780: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
> >ffff888115a31800: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
>                                         ^
>  ffff888115a31880: 00 00 00 00 00 00 02 fc fc fc fc fc fc fc fc fc
>  ffff888115a31900: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ==================================================================
>
>
> ***
>
> KASAN: slab-use-after-free Read in __ext4_check_dir_entry
>
> tree:      torvalds
> URL:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
> arch:      amd64
> compiler:  Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:
> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
> syz repro:
> https://ci.syzbot.org/findings/f1d48ea1-6e87-4d64-9c13-8bf8aed109fc/syz_repro
>
> loop0: lost filesystem error report for type 5 error -117
> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000
> r/w without journal. Quota mode: none.
> ==================================================================
> BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len
> fs/ext4/ext4.h:4069 [inline]
> BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096
> [inline]
> BUG: KASAN: slab-use-after-free in __ext4_check_dir_entry+0x65a/0xc40
> fs/ext4/dir.c:96
> Read of size 1 at addr ffff888114d8c045 by task syz.0.20/5821
>
> CPU: 1 UID: 0 PID: 5821 Comm: syz.0.20 Not tainted syzkaller #0
> PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>  __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
>  ext4_find_dest_de+0x136/0x770 fs/ext4/namei.c:2203
>  ext4_add_dirent_to_inline+0xcf/0x430 fs/ext4/inline.c:984
>  ext4_try_add_inline_entry+0x235/0x8e0 fs/ext4/inline.c:1213
>  __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
>  ext4_add_entry fs/ext4/namei.c:2613 [inline]
>  ext4_add_nondir+0x111/0x310 fs/ext4/namei.c:2936
>  ext4_create+0x2e9/0x470 fs/ext4/namei.c:2982
>  lookup_open fs/namei.c:4511 [inline]
>  open_last_lookups fs/namei.c:4611 [inline]
>  path_openat+0x1395/0x3860 fs/namei.c:4855
>  do_file_open+0x23e/0x4a0 fs/namei.c:4887
>  do_sys_openat2+0x113/0x200 fs/open.c:1364
>  do_sys_open fs/open.c:1370 [inline]
>  __do_sys_openat fs/open.c:1386 [inline]
>  __se_sys_openat fs/open.c:1381 [inline]
>  __x64_sys_openat+0x138/0x170 fs/open.c:1381
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f922219ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f9223137028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 00007f9222415fa0 RCX: 00007f922219ce59
> RDX: 0000000000042042 RSI: 0000200000000080 RDI: 0000000000000004
> RBP: 00007f9222232d6f R08: 0000000000000000 R09: 0000000000000000
> R10: 000000000000014a R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f9222416038 R14: 00007f9222415fa0 R15: 00007ffd01a2d448
>  </TASK>
>
> Allocated by task 5484:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  unpoison_slab_object mm/kasan/common.c:340 [inline]
>  __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
>  kasan_slab_alloc include/linux/kasan.h:253 [inline]
>  slab_post_alloc_hook mm/slub.c:4570 [inline]
>  slab_alloc_node mm/slub.c:4899 [inline]
>  kmem_cache_alloc_node_noprof+0x384/0x690 mm/slub.c:4951
>  kmalloc_reserve net/core/skbuff.c:613 [inline]
>  __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
>  alloc_skb include/linux/skbuff.h:1385 [inline]
>  nlmsg_new include/net/netlink.h:1055 [inline]
>  mpls_netconf_notify_devconf+0x46/0x100 net/mpls/af_mpls.c:1217
>  mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
>  notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
>  call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
>  call_netdevice_notifiers net/core/dev.c:2301 [inline]
>  unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>  process_one_work kernel/workqueue.c:3314 [inline]
>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>
> Freed by task 5484:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
>  poison_slab_object mm/kasan/common.c:253 [inline]
>  __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
>  kasan_slab_free include/linux/kasan.h:235 [inline]
>  slab_free_hook mm/slub.c:2689 [inline]
>  slab_free mm/slub.c:6251 [inline]
>  kfree+0x1c5/0x640 mm/slub.c:6566
>  skb_kfree_head net/core/skbuff.c:1075 [inline]
>  skb_free_head net/core/skbuff.c:1087 [inline]
>  skb_release_data+0x828/0xa60 net/core/skbuff.c:1114
>  skb_release_all net/core/skbuff.c:1189 [inline]
>  __kfree_skb+0x5d/0x210 net/core/skbuff.c:1203
>  netlink_broadcast_filtered+0xe18/0xf20 net/netlink/af_netlink.c:1540
>  nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
>  nlmsg_multicast include/net/netlink.h:1184 [inline]
>  nlmsg_notify+0xf0/0x1a0 net/netlink/af_netlink.c:2598
>  mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
>  notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
>  call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
>  call_netdevice_notifiers net/core/dev.c:2301 [inline]
>  unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>  process_one_work kernel/workqueue.c:3314 [inline]
>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>
> The buggy address belongs to the object at ffff888114d8c000
>  which belongs to the cache skbuff_small_head of size 704
> The buggy address is located 69 bytes inside of
>  freed 704-byte region [ffff888114d8c000, ffff888114d8c2c0)
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x114d8c
> head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
> flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
> page_type: f5(slab)
> raw: 017ff00000000040 ffff888160416b40 dead000000000100 dead000000000122
> raw: 0000000000000000 0000000800120012 00000000f5000000 0000000000000000
> head: 017ff00000000040 ffff888160416b40 dead000000000100 dead000000000122
> head: 0000000000000000 0000000800120012 00000000f5000000 0000000000000000
> head: 017ff00000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff
> head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 2, migratetype Unmovable, gfp_mask
> 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
> pid 5484, tgid 5484 (kworker/u8:2), ts 72573003529, free_ts 72546506446
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>  prep_new_page mm/page_alloc.c:1861 [inline]
>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>  alloc_slab_page mm/slub.c:3278 [inline]
>  allocate_slab+0x77/0x660 mm/slub.c:3467
>  new_slab mm/slub.c:3525 [inline]
>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>  refill_sheaf mm/slub.c:2816 [inline]
>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>  alloc_from_pcs mm/slub.c:4750 [inline]
>  slab_alloc_node mm/slub.c:4884 [inline]
>  kmem_cache_alloc_node_noprof+0x441/0x690 mm/slub.c:4951
>  kmalloc_reserve net/core/skbuff.c:613 [inline]
>  __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
>  alloc_skb include/linux/skbuff.h:1385 [inline]
>  nlmsg_new include/net/netlink.h:1055 [inline]
>  mpls_netconf_notify_devconf+0x46/0x100 net/mpls/af_mpls.c:1217
>  mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
>  notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
>  call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
>  call_netdevice_notifiers net/core/dev.c:2301 [inline]
>  unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>  process_one_work kernel/workqueue.c:3314 [inline]
>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
> page last free pid 5484 tgid 5484 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  __free_pages_prepare mm/page_alloc.c:1397 [inline]
>  __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
>  stack_depot_save_flags+0x40e/0x810 lib/stackdepot.c:735
>  kasan_save_stack mm/kasan/common.c:58 [inline]
>  kasan_save_track+0x4f/0x80 mm/kasan/common.c:78
>  unpoison_slab_object mm/kasan/common.c:340 [inline]
>  __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
>  kasan_slab_alloc include/linux/kasan.h:253 [inline]
>  slab_post_alloc_hook mm/slub.c:4570 [inline]
>  slab_alloc_node mm/slub.c:4899 [inline]
>  kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4906
>  kmem_alloc_batch lib/debugobjects.c:371 [inline]
>  fill_pool+0x156/0x580 lib/debugobjects.c:420
>  debug_objects_fill_pool lib/debugobjects.c:752 [inline]
>  debug_object_activate+0x4a3/0x580 lib/debugobjects.c:841
>  debug_rcu_head_queue kernel/rcu/rcu.h:236 [inline]
>  __call_rcu_common kernel/rcu/tree.c:3116 [inline]
>  call_rcu+0x43/0x890 kernel/rcu/tree.c:3251
>  kernfs_put+0x259/0x520 fs/kernfs/dir.c:618
>  kernfs_remove_by_name_ns+0xc8/0x140 fs/kernfs/dir.c:1799
>  device_remove_class_symlinks+0x178/0x190 drivers/base/core.c:3479
>  device_del+0x400/0x8f0 drivers/base/core.c:3881
>  unregister_netdevice_many_notify+0x1d5f/0x22c0 net/core/dev.c:12456
>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>  process_one_work kernel/workqueue.c:3314 [inline]
>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>
> Memory state around the buggy address:
>  ffff888114d8bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff888114d8bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffff888114d8c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                            ^
>  ffff888114d8c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff888114d8c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> ***
>
> KASAN: slab-use-after-free Read in ext4_inlinedir_to_tree
>
> tree:      torvalds
> URL:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
> arch:      amd64
> compiler:  Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:
> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
> syz repro:
> https://ci.syzbot.org/findings/f42da242-e16e-4f10-bf25-0bd7e192d989/syz_repro
>
> loop0: lost filesystem error report for type 5 error -117
> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000
> r/w without journal. Quota mode: none.
> ==================================================================
> BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len
> fs/ext4/ext4.h:4069 [inline]
> BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096
> [inline]
> BUG: KASAN: slab-use-after-free in ext4_inlinedir_to_tree+0x94c/0x10d0
> fs/ext4/inline.c:1335
> Read of size 1 at addr ffff88816fee8825 by task syz.0.20/5867
>
> CPU: 1 UID: 0 PID: 5867 Comm: syz.0.20 Not tainted syzkaller #0
> PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>  ext4_inlinedir_to_tree+0x94c/0x10d0 fs/ext4/inline.c:1335
>  ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
>  ext4_dx_readdir fs/ext4/dir.c:600 [inline]
>  ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
>  iterate_dir+0x399/0x570 fs/readdir.c:110
>  __do_sys_getdents fs/readdir.c:319 [inline]
>  __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f010ad9ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f010bc0f028 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
> RAX: ffffffffffffffda RBX: 00007f010b015fa0 RCX: 00007f010ad9ce59
> RDX: 0000000000000054 RSI: 0000000000000000 RDI: 0000000000000004
> RBP: 00007f010ae32d6f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f010b016038 R14: 00007f010b015fa0 R15: 00007ffd93577348
>  </TASK>
>
> Allocated by task 5064:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>  __do_kmalloc_node mm/slub.c:5296 [inline]
>  __kmalloc_noprof+0x35c/0x760 mm/slub.c:5308
>  kmalloc_noprof include/linux/slab.h:954 [inline]
>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>  tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
>  tomoyo_encode+0x28b/0x550 security/tomoyo/realpath.c:80
>  tomoyo_realpath_from_path+0x58d/0x5d0 security/tomoyo/realpath.c:283
>  tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
>  tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
>  security_inode_getattr+0x12b/0x310 security/security.c:1895
>  vfs_getattr fs/stat.c:259 [inline]
>  vfs_fstat fs/stat.c:281 [inline]
>  vfs_fstatat+0xb4/0x170 fs/stat.c:371
>  __do_sys_newfstatat fs/stat.c:538 [inline]
>  __se_sys_newfstatat fs/stat.c:532 [inline]
>  __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Freed by task 5064:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
>  poison_slab_object mm/kasan/common.c:253 [inline]
>  __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
>  kasan_slab_free include/linux/kasan.h:235 [inline]
>  slab_free_hook mm/slub.c:2689 [inline]
>  slab_free mm/slub.c:6251 [inline]
>  kfree+0x1c5/0x640 mm/slub.c:6566
>  tomoyo_path_perm+0x403/0x560 security/tomoyo/file.c:847
>  security_inode_getattr+0x12b/0x310 security/security.c:1895
>  vfs_getattr fs/stat.c:259 [inline]
>  vfs_fstat fs/stat.c:281 [inline]
>  vfs_fstatat+0xb4/0x170 fs/stat.c:371
>  __do_sys_newfstatat fs/stat.c:538 [inline]
>  __se_sys_newfstatat fs/stat.c:532 [inline]
>  __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> The buggy address belongs to the object at ffff88816fee8800
>  which belongs to the cache kmalloc-64 of size 64
> The buggy address is located 37 bytes inside of
>  freed 64-byte region [ffff88816fee8800, ffff88816fee8840)
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16fee8
> flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
> page_type: f5(slab)
> raw: 057ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
> raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 0, migratetype Unmovable, gfp_mask
> 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
> pid 1, tgid 1 (swapper/0), ts 21294026082, free_ts 0
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>  prep_new_page mm/page_alloc.c:1861 [inline]
>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>  alloc_slab_page mm/slub.c:3278 [inline]
>  allocate_slab+0x77/0x660 mm/slub.c:3467
>  new_slab mm/slub.c:3525 [inline]
>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>  refill_sheaf mm/slub.c:2816 [inline]
>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>  alloc_from_pcs mm/slub.c:4750 [inline]
>  slab_alloc_node mm/slub.c:4884 [inline]
>  __do_kmalloc_node mm/slub.c:5295 [inline]
>  __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
>  kmalloc_noprof include/linux/slab.h:954 [inline]
>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>  handler_new_ref+0x261/0x9c0 drivers/media/v4l2-core/v4l2-ctrls-core.c:1882
>  v4l2_ctrl_add_handler+0x19f/0x290
> drivers/media/v4l2-core/v4l2-ctrls-core.c:2443
>  vivid_create_controls+0x332d/0x3bd0
> drivers/media/test-drivers/vivid/vivid-ctrls.c:2072
>  vivid_create_instance drivers/media/test-drivers/vivid/vivid-core.c:1933
> [inline]
>  vivid_probe+0x4261/0x72b0
> drivers/media/test-drivers/vivid/vivid-core.c:2095
>  platform_probe+0xf9/0x190 drivers/base/platform.c:1432
>  call_driver_probe drivers/base/dd.c:-1 [inline]
>  really_probe+0x267/0xaf0 drivers/base/dd.c:709
>  __driver_probe_device+0x1ef/0x380 drivers/base/dd.c:871
>  driver_probe_device+0x4f/0x240 drivers/base/dd.c:901
>  __driver_attach+0x34c/0x640 drivers/base/dd.c:1295
> page_owner free stack trace missing
>
> Memory state around the buggy address:
>  ffff88816fee8700: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
>  ffff88816fee8780: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
> >ffff88816fee8800: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>                                ^
>  ffff88816fee8880: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>  ffff88816fee8900: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ==================================================================
>
>
> ***
>
> KASAN: use-after-free Read in __ext4_check_dir_entry
>
> tree:      torvalds
> URL:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
> arch:      amd64
> compiler:  Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:
> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
> syz repro:
> https://ci.syzbot.org/findings/57c0b75a-8922-4dc1-9a20-ca947564792b/syz_repro
>
> ==================================================================
> BUG: KASAN: use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4069
> [inline]
> BUG: KASAN: use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096
> [inline]
> BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x65a/0xc40
> fs/ext4/dir.c:96
> Read of size 1 at addr ffff88816be85045 by task syz.2.21/5880
>
> CPU: 1 UID: 0 PID: 5880 Comm: syz.2.21 Not tainted syzkaller #0
> PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>  __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
>  ext4_find_dest_de+0x136/0x770 fs/ext4/namei.c:2203
>  ext4_add_dirent_to_inline+0xcf/0x430 fs/ext4/inline.c:984
>  ext4_try_add_inline_entry+0x235/0x8e0 fs/ext4/inline.c:1213
>  __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
>  ext4_add_entry fs/ext4/namei.c:2613 [inline]
>  ext4_add_nondir+0x111/0x310 fs/ext4/namei.c:2936
>  ext4_create+0x2e9/0x470 fs/ext4/namei.c:2982
>  lookup_open fs/namei.c:4511 [inline]
>  open_last_lookups fs/namei.c:4611 [inline]
>  path_openat+0x1395/0x3860 fs/namei.c:4855
>  do_file_open+0x23e/0x4a0 fs/namei.c:4887
>  do_sys_openat2+0x113/0x200 fs/open.c:1364
>  do_sys_open fs/open.c:1370 [inline]
>  __do_sys_openat fs/open.c:1386 [inline]
>  __se_sys_openat fs/open.c:1381 [inline]
>  __x64_sys_openat+0x138/0x170 fs/open.c:1381
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f5713b9ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fff672b25f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 00007f5713e15fa0 RCX: 00007f5713b9ce59
> RDX: 0000000000042042 RSI: 0000200000000080 RDI: 0000000000000004
> RBP: 00007f5713c32d6f R08: 0000000000000000 R09: 0000000000000000
> R10: 000000000000014a R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f5713e15fac R14: 00007f5713e15fa0 R15: 00007f5713e15fa0
>  </TASK>
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16be85
> flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
> page_type: f0(buddy)
> raw: 057ff00000000000 ffffea0005afa0c8 ffffea0005afa1c8 0000000000000000
> raw: 0000000000000000 0000000000000000 00000000f0000000 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as freed
> page last allocated via order 0, migratetype Unmovable, gfp_mask
> 0xcc0(GFP_KERNEL), pid 5630, tgid 5630 (syz-executor), ts 67290853657,
> free_ts 69321168948
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>  prep_new_page mm/page_alloc.c:1861 [inline]
>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>  __alloc_pages_noprof+0x10/0x100 mm/page_alloc.c:5255
>  alloc_pages_bulk_noprof+0x5ff/0x7c0 mm/page_alloc.c:5175
>  ___alloc_pages_bulk mm/kasan/shadow.c:345 [inline]
>  __kasan_populate_vmalloc_do mm/kasan/shadow.c:370 [inline]
>  __kasan_populate_vmalloc+0xc1/0x1d0 mm/kasan/shadow.c:424
>  kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
>  alloc_vmap_area+0xd47/0x1480 mm/vmalloc.c:2123
>  __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3226
>  __vmalloc_node_range_noprof+0x36a/0x1750 mm/vmalloc.c:4024
>  vmalloc_user_noprof+0xad/0xe0 mm/vmalloc.c:4218
>  kcov_ioctl+0x55/0x620 kernel/kcov.c:726
>  vfs_ioctl fs/ioctl.c:51 [inline]
>  __do_sys_ioctl fs/ioctl.c:597 [inline]
>  __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> page last free pid 5693 tgid 5693 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  __free_pages_prepare mm/page_alloc.c:1397 [inline]
>  __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
>  kasan_depopulate_vmalloc_pte+0x6d/0x90 mm/kasan/shadow.c:484
>  apply_to_pte_range mm/memory.c:3338 [inline]
>  apply_to_pmd_range mm/memory.c:3382 [inline]
>  apply_to_pud_range mm/memory.c:3418 [inline]
>  apply_to_p4d_range mm/memory.c:3454 [inline]
>  __apply_to_page_range+0xbdc/0x1420 mm/memory.c:3490
>  __kasan_release_vmalloc+0xa2/0xd0 mm/kasan/shadow.c:602
>  kasan_release_vmalloc include/linux/kasan.h:593 [inline]
>  kasan_release_vmalloc_node mm/vmalloc.c:2284 [inline]
>  purge_vmap_node+0x220/0x960 mm/vmalloc.c:2306
>  __purge_vmap_area_lazy+0x779/0xb40 mm/vmalloc.c:2396
>  drain_vmap_area_work+0x27/0x40 mm/vmalloc.c:2430
>  process_one_work kernel/workqueue.c:3314 [inline]
>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>
> Memory state around the buggy address:
>  ffff88816be84f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff88816be84f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffff88816be85000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>                                            ^
>  ffff88816be85080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>  ffff88816be85100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ==================================================================
>
>
> ***
>
> If these findings have caused you to resend the series or submit a
> separate fix, please add the following tag to your commit message:
>   Tested-by: syzbot@syzkaller.appspotmail.com
>
> ---
> This report is generated by a bot. It may contain errors.
> syzbot ci engineers can be reached at syzkaller@googlegroups.com.
>
> To test a patch for this bug, please reply with `#syz test`
> (should be on a separate line).
>
> The patch should be attached to the email.
> Note: arguments like custom git repos and branches are not supported.
>
>

[-- Attachment #1.2: Type: text/html, Size: 49607 bytes --]

[-- Attachment #2: dirdata-syzbot-fix.patch --]
[-- Type: application/octet-stream, Size: 11438 bytes --]

From e3d5c74f1ec0fbefb9a4b9193a474614b98d640a Mon Sep 17 00:00:00 2001
From: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Date: Fri, 19 Jun 2026 09:48:12 -0400
Subject: [PATCH] ext4: fix issues reported by syzbot/CI on the dirdata series

Address the following issues found by automated review of the v2
dirdata patch series:

- dx_get_dx_info() called ext4_dir_entry_len() with dir hardcoded to
  NULL, forcing its blocksize fallback to 4096 regardless of the real
  filesystem blocksize, and never validated that the computed offset
  stayed within the block. Thread the real inode through and reject
  out-of-bounds results.

- get_dx_countlimit() had the same NULL-dir blocksize-fallback bug at
  a separate call site; pass the real inode through there too.

- ext4_dirdata_get() declared a local "dfid" inside the
  EXT4_DIRENT_LUFID branch that shadowed the function's own "dfid"
  output parameter, so the LUFID copy never reached the caller's
  buffer. Rename the local and copy into the real parameter. Also,
  both ext4_dirdata_get() and ext4_dirdata_set() compared offsets
  against the raw on-disk de->rec_len instead of decoding it via
  ext4_rec_len_from_disk(), which is wrong on big-endian hosts and
  mishandles the "0/65535 means full block" sentinel.

- ext4_dirdata_set_lufid() (EXT4_IOC_SET_LUFID) deleted the existing
  directory entry and then tried to re-add it with the new LUFID
  data; if ext4_add_entry() failed, the inode was left with no
  directory entry pointing at it. On failure, attempt to restore the
  original entry, and loudly flag inode corruption if that also
  fails.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
---
 fs/ext4/namei.c | 105 +++++++++++++++++++++++++++++++++++-------------
 1 file changed, 78 insertions(+), 27 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 65c53c08213a..e6f54dba735e 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -412,7 +412,7 @@ static struct dx_countlimit *get_dx_countlimit(struct inode *inode,
 		if (le16_to_cpu(de->rec_len) != (blocksize - rlen))
 			return NULL;
 		/* de->rec_len covers whole dx_root block, calculate actual length */
-		dotdot_rec_len = ext4_dir_entry_len(de, NULL);
+		dotdot_rec_len = ext4_dir_entry_len(de, inode);
 		root = (struct dx_root_info *)(((char *)de + dotdot_rec_len));
 		if (root->reserved_zero ||
 		    root->info_length != sizeof(struct dx_root_info))
@@ -520,13 +520,20 @@ ext4_next_entry(struct ext4_dir_entry_2 *p, unsigned long blocksize)
  * Future: use high four bits of block for coalesce-on-delete flags
  * Mask them off for now.
  */
-static struct dx_root_info *dx_get_dx_info(void *de_buf)
+static struct dx_root_info *dx_get_dx_info(struct inode *dir, void *de_buf)
 {
+	unsigned int blocksize = dir->i_sb->s_blocksize;
+	void *base = de_buf;
+
 	/* get dotdot first */
-	de_buf += ext4_dir_entry_len(de_buf, NULL);
+	de_buf += ext4_dir_entry_len(de_buf, dir);
 
 	/* dx root info is after dotdot entry */
-	de_buf += ext4_dir_entry_len(de_buf, NULL);
+	de_buf += ext4_dir_entry_len(de_buf, dir);
+
+	if (de_buf < base || (char *)de_buf - (char *)base +
+			      sizeof(struct dx_root_info) > blocksize)
+		return ERR_PTR(-EFSCORRUPTED);
 
 	return (struct dx_root_info *)de_buf;
 }
@@ -577,7 +584,9 @@ static inline unsigned dx_root_limit(struct inode *dir,
 	struct dx_root_info *info;
 	unsigned int entry_space;
 
-	info = dx_get_dx_info(dot_de);
+	info = dx_get_dx_info(dir, dot_de);
+	if (IS_ERR(info))
+		return 0;
 	entry_space = dir->i_sb->s_blocksize - ((char *)info - (char *)dot_de) -
 		info->info_length;
 
@@ -793,7 +802,9 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
 	if (IS_ERR(frame->bh))
 		return (struct dx_frame *) frame->bh;
 
-	info = dx_get_dx_info((struct ext4_dir_entry_2 *)frame->bh->b_data);
+	info = dx_get_dx_info(dir, (struct ext4_dir_entry_2 *)frame->bh->b_data);
+	if (IS_ERR(info))
+		goto fail;
 	if (info->hash_version != DX_HASH_TEA &&
 	    info->hash_version != DX_HASH_HALF_MD4 &&
 	    info->hash_version != DX_HASH_LEGACY &&
@@ -938,7 +949,7 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
 	return ret_err;
 }
 
-static void dx_release(struct dx_frame *frames)
+static void dx_release(struct inode *dir, struct dx_frame *frames)
 {
 	struct dx_root_info *info;
 	int i;
@@ -947,7 +958,9 @@ static void dx_release(struct dx_frame *frames)
 	if (frames[0].bh == NULL)
 		return;
 
-	info = dx_get_dx_info((struct ext4_dir_entry_2 *)frames[0].bh->b_data);
+	info = dx_get_dx_info(dir, (struct ext4_dir_entry_2 *)frames[0].bh->b_data);
+	if (IS_ERR(info))
+		return;
 	/* save local copy, "info" may be freed after brelse() */
 	indirect_levels = info->indirect_levels;
 	for (i = 0; i <= indirect_levels; i++) {
@@ -1253,12 +1266,12 @@ int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,
 		    (count && ((hashval & 1) == 0)))
 			break;
 	}
-	dx_release(frames);
+	dx_release(dir, frames);
 	dxtrace(printk(KERN_DEBUG "Fill tree: returned %d entries, "
 		       "next hash: %x\n", count, *next_hash));
 	return count;
 errout:
-	dx_release(frames);
+	dx_release(dir, frames);
 	return (err);
 }
 
@@ -1296,8 +1309,10 @@ unsigned char ext4_dirdata_get(struct ext4_dir_entry_2 *de, struct inode *dir,
 {
 	unsigned char ret = 0;
 	unsigned int data_offset = de->name_len + 1;
+	unsigned int rec_len = ext4_rec_len_from_disk(de->rec_len,
+						       dir->i_sb->s_blocksize);
 
-	if (data_offset > de->rec_len)
+	if (data_offset > rec_len)
 		return ret;
 
 	/* compatibility: hash stored inline after filename (no dirdata) */
@@ -1312,19 +1327,20 @@ unsigned char ext4_dirdata_get(struct ext4_dir_entry_2 *de, struct inode *dir,
 
 	/*  EXT4_DIRENT_* are not expected without flag in i_sb */
 	if (de->file_type & EXT4_DIRENT_LUFID) {
-		struct ext4_dirent_fid *dfid =
+		struct ext4_dirent_fid *disk_fid =
 			(struct ext4_dirent_fid *)(de->name + data_offset);
 		unsigned int dlen;
 
-		if (data_offset + sizeof(dfid->df_header) > de->rec_len)
+		if (data_offset + sizeof(disk_fid->df_header) > rec_len)
 			return ret;
 
-		dlen = dfid->df_header.ddh_length;
-		if (dlen < sizeof(*dfid) || data_offset + dlen > de->rec_len)
+		dlen = disk_fid->df_header.ddh_length;
+		if (dlen < sizeof(*disk_fid) || data_offset + dlen > rec_len)
 			return ret;
 
 		if (dfid) {
-			memcpy(dfid, dfid->df_fid, dfid->df_header.ddh_length);
+			memcpy(dfid, disk_fid->df_fid,
+			       disk_fid->df_header.ddh_length);
 			ret |= EXT4_DIRENT_LUFID;
 		}
 		data_offset += dlen;
@@ -1336,11 +1352,11 @@ unsigned char ext4_dirdata_get(struct ext4_dir_entry_2 *de, struct inode *dir,
 		       (struct ext4_dirent_data_header *)(de->name + data_offset);
 		unsigned int dlen;
 
-		if (data_offset + sizeof(*ddh) > de->rec_len)
+		if (data_offset + sizeof(*ddh) > rec_len)
 			return ret;
 
 		dlen = ddh->ddh_length;
-		if (dlen < sizeof(*ddh) || data_offset + dlen > de->rec_len)
+		if (dlen < sizeof(*ddh) || data_offset + dlen > rec_len)
 			return ret;
 
 		data_offset += dlen;
@@ -1355,7 +1371,7 @@ unsigned char ext4_dirdata_get(struct ext4_dir_entry_2 *de, struct inode *dir,
 		unsigned int dlen;
 
 		dlen = dh->dh_header.ddh_length;
-		if (dlen < sizeof(*dh) || data_offset + dlen > de->rec_len)
+		if (dlen < sizeof(*dh) || data_offset + dlen > rec_len)
 			return ret;
 
 		hinfo->hash = le32_to_cpu(dh->dh_hash.hash);
@@ -1383,12 +1399,14 @@ static void ext4_dirdata_set(struct ext4_dir_entry_2 *de, struct inode *dir,
 {
 	struct dx_hash_info *hinfo = &fname->hinfo;
 	unsigned int data_offset = de->name_len + 1;
+	unsigned int rec_len = ext4_rec_len_from_disk(de->rec_len,
+						       dir->i_sb->s_blocksize);
 
 
 	if (dfid) {
 		unsigned int dlen = dfid->df_header.ddh_length;
 
-		if (data_offset + dlen > de->rec_len) {
+		if (data_offset + dlen > rec_len) {
 			EXT4_ERROR_INODE(dir, "Can not insert FID");
 			return;
 		}
@@ -1406,7 +1424,7 @@ static void ext4_dirdata_set(struct ext4_dir_entry_2 *de, struct inode *dir,
 			struct ext4_dirent_hash *dh =
 			    (struct ext4_dirent_hash *)(de->name + data_offset);
 
-			if (data_offset + sizeof(*dh) > de->rec_len) {
+			if (data_offset + sizeof(*dh) > rec_len) {
 				EXT4_ERROR_INODE(dir, "Can not insert dhash dirdata");
 				return;
 			}
@@ -1418,7 +1436,7 @@ static void ext4_dirdata_set(struct ext4_dir_entry_2 *de, struct inode *dir,
 		} else {
 			/* Compatibility: store hash inline after filename */
 			if (data_offset + sizeof(struct ext4_dir_entry_hash) >
-								de-> rec_len) {
+								rec_len) {
 				EXT4_ERROR_INODE(dir, "Can not insert dhash");
 				return;
 			}
@@ -1906,7 +1924,7 @@ static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
 errout:
 	dxtrace(printk(KERN_DEBUG "%s not found\n", fname->usr_fname->name));
 success:
-	dx_release(frames);
+	dx_release(dir, frames);
 	return bh;
 }
 
@@ -2425,7 +2443,12 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 				     blocksize);
 
 	/* initialize hashing info */
-	dx_info = dx_get_dx_info(dot_de);
+	dx_info = dx_get_dx_info(dir, dot_de);
+	if (IS_ERR(dx_info)) {
+		brelse(bh2);
+		brelse(bh);
+		return PTR_ERR(dx_info);
+	}
 	memset(dx_info, 0, sizeof(*dx_info));
 	dx_info->info_length = sizeof(*dx_info);
 	if (ext4_hash_in_dirent(dir))
@@ -2483,7 +2506,7 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 	 */
 	if (retval)
 		ext4_mark_inode_dirty(handle, dir);
-	dx_release(frames);
+	dx_release(dir, frames);
 	brelse(bh2);
 	return retval;
 }
@@ -2759,8 +2782,13 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname,
 			/* Set up root */
 			dx_set_count(entries, 1);
 			dx_set_block(entries + 0, newblock);
-			info = dx_get_dx_info((struct ext4_dir_entry_2 *)
+			info = dx_get_dx_info(dir, (struct ext4_dir_entry_2 *)
 					      frames[0].bh->b_data);
+			if (IS_ERR(info)) {
+				err = PTR_ERR(info);
+				brelse(bh2);
+				goto journal_error;
+			}
 			info->indirect_levels += 1;
 			dxtrace(printk(KERN_DEBUG
 				       "Creating %d level index...\n",
@@ -2788,7 +2816,7 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname,
 	ext4_std_error(dir->i_sb, err); /* this is a no-op if err == 0 */
 cleanup:
 	brelse(bh);
-	dx_release(frames);
+	dx_release(dir, frames);
 	/* @restart is true means htree-path has been changed, we need to
 	 * repeat dx_probe() to find out valid htree-path
 	 */
@@ -4463,6 +4491,29 @@ int ext4_dirdata_set_lufid(struct inode *dir, const char *filename,
 	}
 	EXT4_I(inode)->i_dirdata = old_dirdata;
 
+	if (err) {
+		/*
+		 * The original entry was already removed above and the
+		 * re-add with the new LUFID failed; try to restore the
+		 * original entry so the inode isn't left without any
+		 * directory entry pointing at it.
+		 */
+		struct dentry parent_dentry = { .d_inode = dir };
+		struct dentry orig_dentry = {
+			.d_name = d_name,
+			.d_parent = &parent_dentry,
+			.d_inode = inode,
+		};
+		int rollback_err = ext4_add_entry(handle, &orig_dentry, inode);
+
+		if (rollback_err)
+			EXT4_ERROR_INODE(dir,
+				"Failed to set LUFID on '%.*s' (err=%d) and failed to restore the original directory entry (err=%d); inode %llu may be orphaned",
+				namelen, filename, err, rollback_err,
+				inode->i_ino);
+		goto out_unlock;
+	}
+
 	/* Update inode times */
 	inode_set_ctime_current(dir);
 	inode_inc_iversion(dir);
-- 
2.43.7

Re: [syzbot ci] Re: Data in direntry (dirdata) feature

[syzbot]

> Thanks for the report. The attached patch addresses the issues found in
> the dirdata series review (dx_get_dx_info/get_dx_countlimit blocksize
> fallback, dfid parameter shadowing in ext4_dirdata_get, and the unsafe
> delete-before-add in EXT4_IOC_SET_LUFID).
>
>
> #syz test

I see the command but can't find the corresponding bug.
The email is sent to  syzbot+HASH@syzkaller.appspotmail.com address
but the HASH does not correspond to any known bug.
Please double check the address.

>
> On Thu, Jun 11, 2026 11:29 AM, syzbot ci <
> syzbot+cid7b922cb3d448114@syzkaller.appspotmail.com> wrote:
>
>> syzbot ci has tested the following series
>>
>> [v2] Data in direntry (dirdata) feature
>>
>> https://lore.kernel.org/all/20260610152417.13576-1-ablagodarenko@thelustrecollective.com
>> * [PATCH v2 01/10] ext4: replace ext4_dir_entry with ext4_dir_entry_2
>> * [PATCH v2 02/10] ext4: add ext4_dir_entry_is_tail()
>> * [PATCH v2 03/10] ext4: refactor dx_root to support variable dirent sizes
>> * [PATCH v2 04/10] ext4: add dirdata format definitions and access helpers
>> * [PATCH v2 05/10] ext4: preserve dirdata bits in get_dtype()
>> * [PATCH v2 06/10] ext4: add ext4_dir_entry_len() and harden dirdata
>> parsing
>> * [PATCH v2 07/10] ext4: rename ext4_dir_rec_len() and clarify dirdata
>> usage
>> * [PATCH v2 08/10] ext4: dirdata feature
>> * [PATCH v2 09/10] ext4: add dirdata set/get helpers
>> * [PATCH v2 10/10] ext4: Add EXT4_IOC_SET_LUFID ioctl for setting LUFID on
>> directory entries
>>
>> and found the following issues:
>> * KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
>> * KASAN: slab-out-of-bounds Read in ext4_inlinedir_to_tree
>> * KASAN: slab-use-after-free Read in __ext4_check_dir_entry
>> * KASAN: slab-use-after-free Read in ext4_inlinedir_to_tree
>> * KASAN: use-after-free Read in __ext4_check_dir_entry
>>
>> Full report is available here:
>> https://ci.syzbot.org/series/5bf0e2fa-2e68-4532-8396-4568879b2788
>>
>> ***
>>
>> KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
>>
>> tree:      torvalds
>> URL:
>> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
>> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
>> arch:      amd64
>> compiler:  Debian clang version 21.1.8
>> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
>> config:
>> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
>> syz repro:
>> https://ci.syzbot.org/findings/b0854918-13f9-49dd-ab30-12154f0debe2/syz_repro
>>
>> loop0: lost filesystem error report for type 5 error -117
>> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000
>> r/w without journal. Quota mode: none.
>> ==================================================================
>> BUG: KASAN: slab-out-of-bounds in ext4_dirent_get_data_len
>> fs/ext4/ext4.h:4069 [inline]
>> BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4096
>> [inline]
>> BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x65a/0xc40
>> fs/ext4/dir.c:96
>> Read of size 1 at addr ffff8881022db7f5 by task syz.0.23/5815
>>
>> CPU: 1 UID: 0 PID: 5815 Comm: syz.0.23 Not tainted syzkaller #0
>> PREEMPT(full)
>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
>> 1.16.2-debian-1.16.2-1 04/01/2014
>> Call Trace:
>>  <TASK>
>>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>>  print_report+0x58/0x70 mm/kasan/report.c:482
>>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>>  __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
>>  ext4_check_all_de+0x66/0x150 fs/ext4/dir.c:657
>>  ext4_convert_inline_data_nolock+0x1b7/0x990 fs/ext4/inline.c:1121
>>  ext4_try_add_inline_entry+0x604/0x8e0 fs/ext4/inline.c:1247
>>  __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
>>  ext4_add_entry fs/ext4/namei.c:2613 [inline]
>>  ext4_mkdir+0x5e5/0xce0 fs/ext4/namei.c:3175
>>  vfs_mkdir+0x413/0x630 fs/namei.c:5271
>>  filename_mkdirat+0x285/0x510 fs/namei.c:5304
>>  __do_sys_mkdirat fs/namei.c:5325 [inline]
>>  __se_sys_mkdirat+0x35/0x150 fs/namei.c:5322
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> RIP: 0033:0x7f669359bcc7
>> Code: 00 66 90 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 db f7 ff
>> ff 66 2e 0f 1f 84 00 00 00 00 00 90 b8 02 01 00 00 0f 05 <48> 3d 01 f0 ff
>> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007ffd42381d38 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
>> RAX: ffffffffffffffda RBX: 00007ffd42381dc0 RCX: 00007f669359bcc7
>> RDX: 00000000000001ff RSI: 0000200000001200 RDI: 00000000ffffff9c
>> RBP: 00002000000024c0 R08: 0000200000000240 R09: 0000000000000000
>> R10: 00002000000024c0 R11: 0000000000000246 R12: 0000200000001200
>> R13: 00007ffd42381d80 R14: 0000000000000000 R15: 0000000000000000
>>  </TASK>
>>
>> Allocated by task 5066:
>>  kasan_save_stack mm/kasan/common.c:57 [inline]
>>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>>  poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
>>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
>>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>>  __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5420
>>  kmalloc_noprof include/linux/slab.h:950 [inline]
>>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>>  kernfs_get_open_node fs/kernfs/file.c:543 [inline]
>>  kernfs_fop_open+0x862/0xda0 fs/kernfs/file.c:718
>>  do_dentry_open+0x822/0x13a0 fs/open.c:947
>>  vfs_open+0x3b/0x340 fs/open.c:1079
>>  do_open fs/namei.c:4699 [inline]
>>  path_openat+0x2e08/0x3860 fs/namei.c:4858
>>  do_file_open+0x23e/0x4a0 fs/namei.c:4887
>>  do_sys_openat2+0x113/0x200 fs/open.c:1364
>>  do_sys_open fs/open.c:1370 [inline]
>>  __do_sys_openat fs/open.c:1386 [inline]
>>  __se_sys_openat fs/open.c:1381 [inline]
>>  __x64_sys_openat+0x138/0x170 fs/open.c:1381
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>>
>> Last potentially related work creation:
>>  kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
>>  kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
>>  kvfree_call_rcu+0x100/0x430 mm/slab_common.c:1970
>>  kernfs_unlink_open_file+0x3fe/0x4b0 fs/kernfs/file.c:604
>>  kernfs_fop_release+0x2eb/0x440 fs/kernfs/file.c:783
>>  __fput+0x44f/0xa60 fs/file_table.c:510
>>  fput_close_sync+0x11f/0x240 fs/file_table.c:615
>>  __do_sys_close fs/open.c:1507 [inline]
>>  __se_sys_close fs/open.c:1492 [inline]
>>  __x64_sys_close+0x7e/0x110 fs/open.c:1492
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>>
>> The buggy address belongs to the object at ffff8881022db700
>>  which belongs to the cache kmalloc-128 of size 128
>> The buggy address is located 117 bytes to the right of
>>  allocated 128-byte region [ffff8881022db700, ffff8881022db780)
>>
>> The buggy address belongs to the physical page:
>> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1022db
>> flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
>> page_type: f5(slab)
>> raw: 017ff00000000000 ffff888100041a00 dead000000000100 dead000000000122
>> raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
>> page dumped because: kasan: bad access detected
>> page_owner tracks the page as allocated
>> page last allocated via order 0, migratetype Unmovable, gfp_mask
>> 0xd2000(__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 0,
>> tgid 0 (swapper/0), ts 2408938923, free_ts 0
>>  set_page_owner include/linux/page_owner.h:32 [inline]
>>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>>  prep_new_page mm/page_alloc.c:1861 [inline]
>>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>>  alloc_slab_page mm/slub.c:3278 [inline]
>>  allocate_slab+0x77/0x660 mm/slub.c:3467
>>  new_slab mm/slub.c:3525 [inline]
>>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>>  refill_sheaf mm/slub.c:2816 [inline]
>>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>>  alloc_from_pcs mm/slub.c:4750 [inline]
>>  slab_alloc_node mm/slub.c:4884 [inline]
>>  __do_kmalloc_node mm/slub.c:5295 [inline]
>>  __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
>>  kmalloc_noprof include/linux/slab.h:954 [inline]
>>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>>  __alloc_empty_sheaf mm/slub.c:2768 [inline]
>>  alloc_empty_sheaf mm/slub.c:2783 [inline]
>>  __pcs_replace_empty_main+0x2df/0x720 mm/slub.c:4647
>>  alloc_from_pcs mm/slub.c:4750 [inline]
>>  slab_alloc_node mm/slub.c:4884 [inline]
>>  kmem_cache_alloc_noprof+0x37d/0x650 mm/slub.c:4906
>>  dup_fd+0x55/0xb40 fs/file.c:390
>>  copy_files+0xc8/0x120 kernel/fork.c:1639
>>  copy_process+0x1d94/0x4440 kernel/fork.c:2252
>>  kernel_clone+0x2d7/0x940 kernel/fork.c:2722
>>  user_mode_thread+0x110/0x180 kernel/fork.c:2798
>>  rest_init+0x23/0x300 init/main.c:727
>>  start_kernel+0x38a/0x3e0 init/main.c:1220
>> page_owner free stack trace missing
>>
>> Memory state around the buggy address:
>>  ffff8881022db680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>  ffff8881022db700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> >ffff8881022db780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>                                                              ^
>>  ffff8881022db800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>  ffff8881022db880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>> ==================================================================
>>
>>
>> ***
>>
>> KASAN: slab-out-of-bounds Read in ext4_inlinedir_to_tree
>>
>> tree:      torvalds
>> URL:
>> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
>> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
>> arch:      amd64
>> compiler:  Debian clang version 21.1.8
>> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
>> config:
>> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
>> syz repro:
>> https://ci.syzbot.org/findings/2dff870b-f382-4c93-8d8d-b2291d921224/syz_repro
>>
>> loop1: lost filesystem error report for type 5 error -117
>> EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000
>> r/w without journal. Quota mode: none.
>> ==================================================================
>> BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4095
>> [inline]
>> BUG: KASAN: slab-out-of-bounds in ext4_inlinedir_to_tree+0xda5/0x10d0
>> fs/ext4/inline.c:1335
>> Read of size 2 at addr ffff888115a3183c by task syz.1.18/5839
>>
>> CPU: 1 UID: 0 PID: 5839 Comm: syz.1.18 Not tainted syzkaller #0
>> PREEMPT(full)
>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
>> 1.16.2-debian-1.16.2-1 04/01/2014
>> Call Trace:
>>  <TASK>
>>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>>  print_report+0x58/0x70 mm/kasan/report.c:482
>>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>>  ext4_dir_entry_len fs/ext4/ext4.h:4095 [inline]
>>  ext4_inlinedir_to_tree+0xda5/0x10d0 fs/ext4/inline.c:1335
>>  ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
>>  ext4_dx_readdir fs/ext4/dir.c:600 [inline]
>>  ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
>>  iterate_dir+0x399/0x570 fs/readdir.c:110
>>  __do_sys_getdents64 fs/readdir.c:399 [inline]
>>  __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> RIP: 0033:0x7f3e02b9ce59
>> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
>> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
>> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007f3e03ad5028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
>> RAX: ffffffffffffffda RBX: 00007f3e02e15fa0 RCX: 00007f3e02b9ce59
>> RDX: 0000000000001000 RSI: 0000200000000f80 RDI: 0000000000000004
>> RBP: 00007f3e02c32d6f R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>> R13: 00007f3e02e16038 R14: 00007f3e02e15fa0 R15: 00007ffcaa902298
>>  </TASK>
>>
>> Allocated by task 5839:
>>  kasan_save_stack mm/kasan/common.c:57 [inline]
>>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>>  poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
>>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
>>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>>  __do_kmalloc_node mm/slub.c:5296 [inline]
>>  __kmalloc_noprof+0x35c/0x760 mm/slub.c:5308
>>  kmalloc_noprof include/linux/slab.h:954 [inline]
>>  ext4_inlinedir_to_tree+0x312/0x10d0 fs/ext4/inline.c:1292
>>  ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
>>  ext4_dx_readdir fs/ext4/dir.c:600 [inline]
>>  ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
>>  iterate_dir+0x399/0x570 fs/readdir.c:110
>>  __do_sys_getdents64 fs/readdir.c:399 [inline]
>>  __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>>
>> The buggy address belongs to the object at ffff888115a31800
>>  which belongs to the cache kmalloc-64 of size 64
>> The buggy address is located 0 bytes to the right of
>>  allocated 60-byte region [ffff888115a31800, ffff888115a3183c)
>>
>> The buggy address belongs to the physical page:
>> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x115a31
>> flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
>> page_type: f5(slab)
>> raw: 017ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
>> raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
>> page dumped because: kasan: bad access detected
>> page_owner tracks the page as allocated
>> page last allocated via order 0, migratetype Unmovable, gfp_mask
>> 0xd2c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
>> pid 5051, tgid 5051 (acpid), ts 27203740677, free_ts 27201732767
>>  set_page_owner include/linux/page_owner.h:32 [inline]
>>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>>  prep_new_page mm/page_alloc.c:1861 [inline]
>>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>>  alloc_slab_page mm/slub.c:3278 [inline]
>>  allocate_slab+0x77/0x660 mm/slub.c:3467
>>  new_slab mm/slub.c:3525 [inline]
>>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>>  refill_sheaf mm/slub.c:2816 [inline]
>>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>>  alloc_from_pcs mm/slub.c:4750 [inline]
>>  slab_alloc_node mm/slub.c:4884 [inline]
>>  __do_kmalloc_node mm/slub.c:5295 [inline]
>>  __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
>>  kmalloc_noprof include/linux/slab.h:954 [inline]
>>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>>  tomoyo_get_name+0x20c/0x590 security/tomoyo/memory.c:173
>>  tomoyo_parse_name_union+0xd9/0x130 security/tomoyo/util.c:260
>>  tomoyo_update_path_acl security/tomoyo/file.c:399 [inline]
>>  tomoyo_write_file+0x3a6/0xc50 security/tomoyo/file.c:1027
>>  tomoyo_write_domain2 security/tomoyo/common.c:1160 [inline]
>>  tomoyo_add_entry security/tomoyo/common.c:2177 [inline]
>>  tomoyo_supervisor+0x1208/0x1570 security/tomoyo/common.c:2238
>>  tomoyo_audit_path_log security/tomoyo/file.c:169 [inline]
>>  tomoyo_path_permission+0x25a/0x380 security/tomoyo/file.c:592
>>  tomoyo_check_open_permission+0x2b2/0x470 security/tomoyo/file.c:782
>>  security_file_open+0xa9/0x240 security/security.c:2739
>>  do_dentry_open+0x4a8/0x13a0 fs/open.c:924
>>  vfs_open+0x3b/0x340 fs/open.c:1079
>> page last free pid 15 tgid 15 stack trace:
>>  reset_page_owner include/linux/page_owner.h:25 [inline]
>>  __free_pages_prepare mm/page_alloc.c:1397 [inline]
>>  __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
>>  __tlb_remove_table_free mm/mmu_gather.c:228 [inline]
>>  tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:291
>>  rcu_do_batch kernel/rcu/tree.c:2617 [inline]
>>  rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
>>  handle_softirqs+0x22a/0x840 kernel/softirq.c:622
>>  run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
>>  smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
>>  kthread+0x389/0x470 kernel/kthread.c:436
>>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>>
>> Memory state around the buggy address:
>>  ffff888115a31700: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>>  ffff888115a31780: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
>> >ffff888115a31800: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
>>                                         ^
>>  ffff888115a31880: 00 00 00 00 00 00 02 fc fc fc fc fc fc fc fc fc
>>  ffff888115a31900: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>> ==================================================================
>>
>>
>> ***
>>
>> KASAN: slab-use-after-free Read in __ext4_check_dir_entry
>>
>> tree:      torvalds
>> URL:
>> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
>> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
>> arch:      amd64
>> compiler:  Debian clang version 21.1.8
>> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
>> config:
>> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
>> syz repro:
>> https://ci.syzbot.org/findings/f1d48ea1-6e87-4d64-9c13-8bf8aed109fc/syz_repro
>>
>> loop0: lost filesystem error report for type 5 error -117
>> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000
>> r/w without journal. Quota mode: none.
>> ==================================================================
>> BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len
>> fs/ext4/ext4.h:4069 [inline]
>> BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096
>> [inline]
>> BUG: KASAN: slab-use-after-free in __ext4_check_dir_entry+0x65a/0xc40
>> fs/ext4/dir.c:96
>> Read of size 1 at addr ffff888114d8c045 by task syz.0.20/5821
>>
>> CPU: 1 UID: 0 PID: 5821 Comm: syz.0.20 Not tainted syzkaller #0
>> PREEMPT(full)
>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
>> 1.16.2-debian-1.16.2-1 04/01/2014
>> Call Trace:
>>  <TASK>
>>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>>  print_report+0x58/0x70 mm/kasan/report.c:482
>>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>>  __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
>>  ext4_find_dest_de+0x136/0x770 fs/ext4/namei.c:2203
>>  ext4_add_dirent_to_inline+0xcf/0x430 fs/ext4/inline.c:984
>>  ext4_try_add_inline_entry+0x235/0x8e0 fs/ext4/inline.c:1213
>>  __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
>>  ext4_add_entry fs/ext4/namei.c:2613 [inline]
>>  ext4_add_nondir+0x111/0x310 fs/ext4/namei.c:2936
>>  ext4_create+0x2e9/0x470 fs/ext4/namei.c:2982
>>  lookup_open fs/namei.c:4511 [inline]
>>  open_last_lookups fs/namei.c:4611 [inline]
>>  path_openat+0x1395/0x3860 fs/namei.c:4855
>>  do_file_open+0x23e/0x4a0 fs/namei.c:4887
>>  do_sys_openat2+0x113/0x200 fs/open.c:1364
>>  do_sys_open fs/open.c:1370 [inline]
>>  __do_sys_openat fs/open.c:1386 [inline]
>>  __se_sys_openat fs/open.c:1381 [inline]
>>  __x64_sys_openat+0x138/0x170 fs/open.c:1381
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> RIP: 0033:0x7f922219ce59
>> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
>> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
>> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007f9223137028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
>> RAX: ffffffffffffffda RBX: 00007f9222415fa0 RCX: 00007f922219ce59
>> RDX: 0000000000042042 RSI: 0000200000000080 RDI: 0000000000000004
>> RBP: 00007f9222232d6f R08: 0000000000000000 R09: 0000000000000000
>> R10: 000000000000014a R11: 0000000000000246 R12: 0000000000000000
>> R13: 00007f9222416038 R14: 00007f9222415fa0 R15: 00007ffd01a2d448
>>  </TASK>
>>
>> Allocated by task 5484:
>>  kasan_save_stack mm/kasan/common.c:57 [inline]
>>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>>  unpoison_slab_object mm/kasan/common.c:340 [inline]
>>  __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
>>  kasan_slab_alloc include/linux/kasan.h:253 [inline]
>>  slab_post_alloc_hook mm/slub.c:4570 [inline]
>>  slab_alloc_node mm/slub.c:4899 [inline]
>>  kmem_cache_alloc_node_noprof+0x384/0x690 mm/slub.c:4951
>>  kmalloc_reserve net/core/skbuff.c:613 [inline]
>>  __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
>>  alloc_skb include/linux/skbuff.h:1385 [inline]
>>  nlmsg_new include/net/netlink.h:1055 [inline]
>>  mpls_netconf_notify_devconf+0x46/0x100 net/mpls/af_mpls.c:1217
>>  mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
>>  notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
>>  call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
>>  call_netdevice_notifiers net/core/dev.c:2301 [inline]
>>  unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
>>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>>  process_one_work kernel/workqueue.c:3314 [inline]
>>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>>  kthread+0x389/0x470 kernel/kthread.c:436
>>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>>
>> Freed by task 5484:
>>  kasan_save_stack mm/kasan/common.c:57 [inline]
>>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>>  kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
>>  poison_slab_object mm/kasan/common.c:253 [inline]
>>  __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
>>  kasan_slab_free include/linux/kasan.h:235 [inline]
>>  slab_free_hook mm/slub.c:2689 [inline]
>>  slab_free mm/slub.c:6251 [inline]
>>  kfree+0x1c5/0x640 mm/slub.c:6566
>>  skb_kfree_head net/core/skbuff.c:1075 [inline]
>>  skb_free_head net/core/skbuff.c:1087 [inline]
>>  skb_release_data+0x828/0xa60 net/core/skbuff.c:1114
>>  skb_release_all net/core/skbuff.c:1189 [inline]
>>  __kfree_skb+0x5d/0x210 net/core/skbuff.c:1203
>>  netlink_broadcast_filtered+0xe18/0xf20 net/netlink/af_netlink.c:1540
>>  nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
>>  nlmsg_multicast include/net/netlink.h:1184 [inline]
>>  nlmsg_notify+0xf0/0x1a0 net/netlink/af_netlink.c:2598
>>  mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
>>  notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
>>  call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
>>  call_netdevice_notifiers net/core/dev.c:2301 [inline]
>>  unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
>>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>>  process_one_work kernel/workqueue.c:3314 [inline]
>>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>>  kthread+0x389/0x470 kernel/kthread.c:436
>>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>>
>> The buggy address belongs to the object at ffff888114d8c000
>>  which belongs to the cache skbuff_small_head of size 704
>> The buggy address is located 69 bytes inside of
>>  freed 704-byte region [ffff888114d8c000, ffff888114d8c2c0)
>>
>> The buggy address belongs to the physical page:
>> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x114d8c
>> head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
>> flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
>> page_type: f5(slab)
>> raw: 017ff00000000040 ffff888160416b40 dead000000000100 dead000000000122
>> raw: 0000000000000000 0000000800120012 00000000f5000000 0000000000000000
>> head: 017ff00000000040 ffff888160416b40 dead000000000100 dead000000000122
>> head: 0000000000000000 0000000800120012 00000000f5000000 0000000000000000
>> head: 017ff00000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff
>> head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
>> page dumped because: kasan: bad access detected
>> page_owner tracks the page as allocated
>> page last allocated via order 2, migratetype Unmovable, gfp_mask
>> 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
>> pid 5484, tgid 5484 (kworker/u8:2), ts 72573003529, free_ts 72546506446
>>  set_page_owner include/linux/page_owner.h:32 [inline]
>>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>>  prep_new_page mm/page_alloc.c:1861 [inline]
>>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>>  alloc_slab_page mm/slub.c:3278 [inline]
>>  allocate_slab+0x77/0x660 mm/slub.c:3467
>>  new_slab mm/slub.c:3525 [inline]
>>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>>  refill_sheaf mm/slub.c:2816 [inline]
>>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>>  alloc_from_pcs mm/slub.c:4750 [inline]
>>  slab_alloc_node mm/slub.c:4884 [inline]
>>  kmem_cache_alloc_node_noprof+0x441/0x690 mm/slub.c:4951
>>  kmalloc_reserve net/core/skbuff.c:613 [inline]
>>  __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
>>  alloc_skb include/linux/skbuff.h:1385 [inline]
>>  nlmsg_new include/net/netlink.h:1055 [inline]
>>  mpls_netconf_notify_devconf+0x46/0x100 net/mpls/af_mpls.c:1217
>>  mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
>>  notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
>>  call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
>>  call_netdevice_notifiers net/core/dev.c:2301 [inline]
>>  unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
>>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>>  process_one_work kernel/workqueue.c:3314 [inline]
>>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>> page last free pid 5484 tgid 5484 stack trace:
>>  reset_page_owner include/linux/page_owner.h:25 [inline]
>>  __free_pages_prepare mm/page_alloc.c:1397 [inline]
>>  __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
>>  stack_depot_save_flags+0x40e/0x810 lib/stackdepot.c:735
>>  kasan_save_stack mm/kasan/common.c:58 [inline]
>>  kasan_save_track+0x4f/0x80 mm/kasan/common.c:78
>>  unpoison_slab_object mm/kasan/common.c:340 [inline]
>>  __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
>>  kasan_slab_alloc include/linux/kasan.h:253 [inline]
>>  slab_post_alloc_hook mm/slub.c:4570 [inline]
>>  slab_alloc_node mm/slub.c:4899 [inline]
>>  kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4906
>>  kmem_alloc_batch lib/debugobjects.c:371 [inline]
>>  fill_pool+0x156/0x580 lib/debugobjects.c:420
>>  debug_objects_fill_pool lib/debugobjects.c:752 [inline]
>>  debug_object_activate+0x4a3/0x580 lib/debugobjects.c:841
>>  debug_rcu_head_queue kernel/rcu/rcu.h:236 [inline]
>>  __call_rcu_common kernel/rcu/tree.c:3116 [inline]
>>  call_rcu+0x43/0x890 kernel/rcu/tree.c:3251
>>  kernfs_put+0x259/0x520 fs/kernfs/dir.c:618
>>  kernfs_remove_by_name_ns+0xc8/0x140 fs/kernfs/dir.c:1799
>>  device_remove_class_symlinks+0x178/0x190 drivers/base/core.c:3479
>>  device_del+0x400/0x8f0 drivers/base/core.c:3881
>>  unregister_netdevice_many_notify+0x1d5f/0x22c0 net/core/dev.c:12456
>>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>>  process_one_work kernel/workqueue.c:3314 [inline]
>>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>>
>> Memory state around the buggy address:
>>  ffff888114d8bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>  ffff888114d8bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> >ffff888114d8c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>                                            ^
>>  ffff888114d8c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  ffff888114d8c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ==================================================================
>>
>>
>> ***
>>
>> KASAN: slab-use-after-free Read in ext4_inlinedir_to_tree
>>
>> tree:      torvalds
>> URL:
>> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
>> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
>> arch:      amd64
>> compiler:  Debian clang version 21.1.8
>> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
>> config:
>> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
>> syz repro:
>> https://ci.syzbot.org/findings/f42da242-e16e-4f10-bf25-0bd7e192d989/syz_repro
>>
>> loop0: lost filesystem error report for type 5 error -117
>> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000
>> r/w without journal. Quota mode: none.
>> ==================================================================
>> BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len
>> fs/ext4/ext4.h:4069 [inline]
>> BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096
>> [inline]
>> BUG: KASAN: slab-use-after-free in ext4_inlinedir_to_tree+0x94c/0x10d0
>> fs/ext4/inline.c:1335
>> Read of size 1 at addr ffff88816fee8825 by task syz.0.20/5867
>>
>> CPU: 1 UID: 0 PID: 5867 Comm: syz.0.20 Not tainted syzkaller #0
>> PREEMPT(full)
>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
>> 1.16.2-debian-1.16.2-1 04/01/2014
>> Call Trace:
>>  <TASK>
>>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>>  print_report+0x58/0x70 mm/kasan/report.c:482
>>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>>  ext4_inlinedir_to_tree+0x94c/0x10d0 fs/ext4/inline.c:1335
>>  ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
>>  ext4_dx_readdir fs/ext4/dir.c:600 [inline]
>>  ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
>>  iterate_dir+0x399/0x570 fs/readdir.c:110
>>  __do_sys_getdents fs/readdir.c:319 [inline]
>>  __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> RIP: 0033:0x7f010ad9ce59
>> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
>> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
>> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007f010bc0f028 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
>> RAX: ffffffffffffffda RBX: 00007f010b015fa0 RCX: 00007f010ad9ce59
>> RDX: 0000000000000054 RSI: 0000000000000000 RDI: 0000000000000004
>> RBP: 00007f010ae32d6f R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>> R13: 00007f010b016038 R14: 00007f010b015fa0 R15: 00007ffd93577348
>>  </TASK>
>>
>> Allocated by task 5064:
>>  kasan_save_stack mm/kasan/common.c:57 [inline]
>>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>>  poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
>>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
>>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>>  __do_kmalloc_node mm/slub.c:5296 [inline]
>>  __kmalloc_noprof+0x35c/0x760 mm/slub.c:5308
>>  kmalloc_noprof include/linux/slab.h:954 [inline]
>>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>>  tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
>>  tomoyo_encode+0x28b/0x550 security/tomoyo/realpath.c:80
>>  tomoyo_realpath_from_path+0x58d/0x5d0 security/tomoyo/realpath.c:283
>>  tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
>>  tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
>>  security_inode_getattr+0x12b/0x310 security/security.c:1895
>>  vfs_getattr fs/stat.c:259 [inline]
>>  vfs_fstat fs/stat.c:281 [inline]
>>  vfs_fstatat+0xb4/0x170 fs/stat.c:371
>>  __do_sys_newfstatat fs/stat.c:538 [inline]
>>  __se_sys_newfstatat fs/stat.c:532 [inline]
>>  __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>>
>> Freed by task 5064:
>>  kasan_save_stack mm/kasan/common.c:57 [inline]
>>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>>  kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
>>  poison_slab_object mm/kasan/common.c:253 [inline]
>>  __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
>>  kasan_slab_free include/linux/kasan.h:235 [inline]
>>  slab_free_hook mm/slub.c:2689 [inline]
>>  slab_free mm/slub.c:6251 [inline]
>>  kfree+0x1c5/0x640 mm/slub.c:6566
>>  tomoyo_path_perm+0x403/0x560 security/tomoyo/file.c:847
>>  security_inode_getattr+0x12b/0x310 security/security.c:1895
>>  vfs_getattr fs/stat.c:259 [inline]
>>  vfs_fstat fs/stat.c:281 [inline]
>>  vfs_fstatat+0xb4/0x170 fs/stat.c:371
>>  __do_sys_newfstatat fs/stat.c:538 [inline]
>>  __se_sys_newfstatat fs/stat.c:532 [inline]
>>  __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>>
>> The buggy address belongs to the object at ffff88816fee8800
>>  which belongs to the cache kmalloc-64 of size 64
>> The buggy address is located 37 bytes inside of
>>  freed 64-byte region [ffff88816fee8800, ffff88816fee8840)
>>
>> The buggy address belongs to the physical page:
>> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16fee8
>> flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
>> page_type: f5(slab)
>> raw: 057ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
>> raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
>> page dumped because: kasan: bad access detected
>> page_owner tracks the page as allocated
>> page last allocated via order 0, migratetype Unmovable, gfp_mask
>> 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
>> pid 1, tgid 1 (swapper/0), ts 21294026082, free_ts 0
>>  set_page_owner include/linux/page_owner.h:32 [inline]
>>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>>  prep_new_page mm/page_alloc.c:1861 [inline]
>>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>>  alloc_slab_page mm/slub.c:3278 [inline]
>>  allocate_slab+0x77/0x660 mm/slub.c:3467
>>  new_slab mm/slub.c:3525 [inline]
>>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>>  refill_sheaf mm/slub.c:2816 [inline]
>>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>>  alloc_from_pcs mm/slub.c:4750 [inline]
>>  slab_alloc_node mm/slub.c:4884 [inline]
>>  __do_kmalloc_node mm/slub.c:5295 [inline]
>>  __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
>>  kmalloc_noprof include/linux/slab.h:954 [inline]
>>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>>  handler_new_ref+0x261/0x9c0 drivers/media/v4l2-core/v4l2-ctrls-core.c:1882
>>  v4l2_ctrl_add_handler+0x19f/0x290
>> drivers/media/v4l2-core/v4l2-ctrls-core.c:2443
>>  vivid_create_controls+0x332d/0x3bd0
>> drivers/media/test-drivers/vivid/vivid-ctrls.c:2072
>>  vivid_create_instance drivers/media/test-drivers/vivid/vivid-core.c:1933
>> [inline]
>>  vivid_probe+0x4261/0x72b0
>> drivers/media/test-drivers/vivid/vivid-core.c:2095
>>  platform_probe+0xf9/0x190 drivers/base/platform.c:1432
>>  call_driver_probe drivers/base/dd.c:-1 [inline]
>>  really_probe+0x267/0xaf0 drivers/base/dd.c:709
>>  __driver_probe_device+0x1ef/0x380 drivers/base/dd.c:871
>>  driver_probe_device+0x4f/0x240 drivers/base/dd.c:901
>>  __driver_attach+0x34c/0x640 drivers/base/dd.c:1295
>> page_owner free stack trace missing
>>
>> Memory state around the buggy address:
>>  ffff88816fee8700: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
>>  ffff88816fee8780: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>> >ffff88816fee8800: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>>                                ^
>>  ffff88816fee8880: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>>  ffff88816fee8900: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>> ==================================================================
>>
>>
>> ***
>>
>> KASAN: use-after-free Read in __ext4_check_dir_entry
>>
>> tree:      torvalds
>> URL:
>> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
>> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
>> arch:      amd64
>> compiler:  Debian clang version 21.1.8
>> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
>> config:
>> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
>> syz repro:
>> https://ci.syzbot.org/findings/57c0b75a-8922-4dc1-9a20-ca947564792b/syz_repro
>>
>> ==================================================================
>> BUG: KASAN: use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4069
>> [inline]
>> BUG: KASAN: use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096
>> [inline]
>> BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x65a/0xc40
>> fs/ext4/dir.c:96
>> Read of size 1 at addr ffff88816be85045 by task syz.2.21/5880
>>
>> CPU: 1 UID: 0 PID: 5880 Comm: syz.2.21 Not tainted syzkaller #0
>> PREEMPT(full)
>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
>> 1.16.2-debian-1.16.2-1 04/01/2014
>> Call Trace:
>>  <TASK>
>>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>>  print_report+0x58/0x70 mm/kasan/report.c:482
>>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>>  __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
>>  ext4_find_dest_de+0x136/0x770 fs/ext4/namei.c:2203
>>  ext4_add_dirent_to_inline+0xcf/0x430 fs/ext4/inline.c:984
>>  ext4_try_add_inline_entry+0x235/0x8e0 fs/ext4/inline.c:1213
>>  __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
>>  ext4_add_entry fs/ext4/namei.c:2613 [inline]
>>  ext4_add_nondir+0x111/0x310 fs/ext4/namei.c:2936
>>  ext4_create+0x2e9/0x470 fs/ext4/namei.c:2982
>>  lookup_open fs/namei.c:4511 [inline]
>>  open_last_lookups fs/namei.c:4611 [inline]
>>  path_openat+0x1395/0x3860 fs/namei.c:4855
>>  do_file_open+0x23e/0x4a0 fs/namei.c:4887
>>  do_sys_openat2+0x113/0x200 fs/open.c:1364
>>  do_sys_open fs/open.c:1370 [inline]
>>  __do_sys_openat fs/open.c:1386 [inline]
>>  __se_sys_openat fs/open.c:1381 [inline]
>>  __x64_sys_openat+0x138/0x170 fs/open.c:1381
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> RIP: 0033:0x7f5713b9ce59
>> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
>> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
>> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007fff672b25f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
>> RAX: ffffffffffffffda RBX: 00007f5713e15fa0 RCX: 00007f5713b9ce59
>> RDX: 0000000000042042 RSI: 0000200000000080 RDI: 0000000000000004
>> RBP: 00007f5713c32d6f R08: 0000000000000000 R09: 0000000000000000
>> R10: 000000000000014a R11: 0000000000000246 R12: 0000000000000000
>> R13: 00007f5713e15fac R14: 00007f5713e15fa0 R15: 00007f5713e15fa0
>>  </TASK>
>>
>> The buggy address belongs to the physical page:
>> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16be85
>> flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
>> page_type: f0(buddy)
>> raw: 057ff00000000000 ffffea0005afa0c8 ffffea0005afa1c8 0000000000000000
>> raw: 0000000000000000 0000000000000000 00000000f0000000 0000000000000000
>> page dumped because: kasan: bad access detected
>> page_owner tracks the page as freed
>> page last allocated via order 0, migratetype Unmovable, gfp_mask
>> 0xcc0(GFP_KERNEL), pid 5630, tgid 5630 (syz-executor), ts 67290853657,
>> free_ts 69321168948
>>  set_page_owner include/linux/page_owner.h:32 [inline]
>>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>>  prep_new_page mm/page_alloc.c:1861 [inline]
>>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>>  __alloc_pages_noprof+0x10/0x100 mm/page_alloc.c:5255
>>  alloc_pages_bulk_noprof+0x5ff/0x7c0 mm/page_alloc.c:5175
>>  ___alloc_pages_bulk mm/kasan/shadow.c:345 [inline]
>>  __kasan_populate_vmalloc_do mm/kasan/shadow.c:370 [inline]
>>  __kasan_populate_vmalloc+0xc1/0x1d0 mm/kasan/shadow.c:424
>>  kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
>>  alloc_vmap_area+0xd47/0x1480 mm/vmalloc.c:2123
>>  __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3226
>>  __vmalloc_node_range_noprof+0x36a/0x1750 mm/vmalloc.c:4024
>>  vmalloc_user_noprof+0xad/0xe0 mm/vmalloc.c:4218
>>  kcov_ioctl+0x55/0x620 kernel/kcov.c:726
>>  vfs_ioctl fs/ioctl.c:51 [inline]
>>  __do_sys_ioctl fs/ioctl.c:597 [inline]
>>  __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> page last free pid 5693 tgid 5693 stack trace:
>>  reset_page_owner include/linux/page_owner.h:25 [inline]
>>  __free_pages_prepare mm/page_alloc.c:1397 [inline]
>>  __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
>>  kasan_depopulate_vmalloc_pte+0x6d/0x90 mm/kasan/shadow.c:484
>>  apply_to_pte_range mm/memory.c:3338 [inline]
>>  apply_to_pmd_range mm/memory.c:3382 [inline]
>>  apply_to_pud_range mm/memory.c:3418 [inline]
>>  apply_to_p4d_range mm/memory.c:3454 [inline]
>>  __apply_to_page_range+0xbdc/0x1420 mm/memory.c:3490
>>  __kasan_release_vmalloc+0xa2/0xd0 mm/kasan/shadow.c:602
>>  kasan_release_vmalloc include/linux/kasan.h:593 [inline]
>>  kasan_release_vmalloc_node mm/vmalloc.c:2284 [inline]
>>  purge_vmap_node+0x220/0x960 mm/vmalloc.c:2306
>>  __purge_vmap_area_lazy+0x779/0xb40 mm/vmalloc.c:2396
>>  drain_vmap_area_work+0x27/0x40 mm/vmalloc.c:2430
>>  process_one_work kernel/workqueue.c:3314 [inline]
>>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>>  kthread+0x389/0x470 kernel/kthread.c:436
>>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>>
>> Memory state around the buggy address:
>>  ffff88816be84f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>  ffff88816be84f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>> >ffff88816be85000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>>                                            ^
>>  ffff88816be85080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>>  ffff88816be85100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>> ==================================================================
>>
>>
>> ***
>>
>> If these findings have caused you to resend the series or submit a
>> separate fix, please add the following tag to your commit message:
>>   Tested-by: syzbot@syzkaller.appspotmail.com
>>
>> ---
>> This report is generated by a bot. It may contain errors.
>> syzbot ci engineers can be reached at syzkaller@googlegroups.com.
>>
>> To test a patch for this bug, please reply with `#syz test`
>> (should be on a separate line).
>>
>> The patch should be attached to the email.
>> Note: arguments like custom git repos and branches are not supported.
>>
>>
>
> -- 
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/syzkaller-bugs/CA%2BrD4x_2wXOP%3D4RwPY-A2vJjK4Vv9hGUSVFzprCe1H%2B8MTOKhA%40mail.gmail.com.

[syzbot ci] Re: Data in direntry (dirdata) feature

[syzbot ci]

syzbot ci has tested the suggested fix patch on top of the following series:

[v2] Data in direntry (dirdata) feature
https://lore.kernel.org/all/20260610152417.13576-1-ablagodarenko@thelustrecollective.com

Patch: https://ci.syzbot.org/jobs/2471bcf5-fa8b-4932-846b-3db72cc2b56c/patch
Testing results:
* [build 0] Build Patched: passed
* [build 0] Boot test: Patched: passed

Full report is available here:
https://ci.syzbot.org/session/08769134-a853-4686-a652-a4c24e8773d7

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.

Re: [syzbot ci] Re: Data in direntry (dirdata) feature

[Artem Blagodarenko]

[-- Attachment #1.1: Type: text/plain, Size: 44745 bytes --]

Re-sending with the correct recipient address (the prior attempt's #syz
test was bounced for not addressing the bug-specific hash).

Patch addressing the issues found in the dirdata series review
(dx_get_dx_info/get_dx_countlimit blocksize fallback, dfid parameter
shadowing in ext4_dirdata_get, and the unsafe delete-before-add in
EXT4_IOC_SET_LUFID) is attached. Please attach it manually before sending —
see note below.

#syz test

On Thu, Jun 11, 2026 11:29 AM, syzbot ci <
syzbot+cid7b922cb3d448114@syzkaller.appspotmail.com> wrote:

> syzbot ci has tested the following series
>
> [v2] Data in direntry (dirdata) feature
>
> https://lore.kernel.org/all/20260610152417.13576-1-ablagodarenko@thelustrecollective.com
> * [PATCH v2 01/10] ext4: replace ext4_dir_entry with ext4_dir_entry_2
> * [PATCH v2 02/10] ext4: add ext4_dir_entry_is_tail()
> * [PATCH v2 03/10] ext4: refactor dx_root to support variable dirent sizes
> * [PATCH v2 04/10] ext4: add dirdata format definitions and access helpers
> * [PATCH v2 05/10] ext4: preserve dirdata bits in get_dtype()
> * [PATCH v2 06/10] ext4: add ext4_dir_entry_len() and harden dirdata
> parsing
> * [PATCH v2 07/10] ext4: rename ext4_dir_rec_len() and clarify dirdata
> usage
> * [PATCH v2 08/10] ext4: dirdata feature
> * [PATCH v2 09/10] ext4: add dirdata set/get helpers
> * [PATCH v2 10/10] ext4: Add EXT4_IOC_SET_LUFID ioctl for setting LUFID on
> directory entries
>
> and found the following issues:
> * KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
> * KASAN: slab-out-of-bounds Read in ext4_inlinedir_to_tree
> * KASAN: slab-use-after-free Read in __ext4_check_dir_entry
> * KASAN: slab-use-after-free Read in ext4_inlinedir_to_tree
> * KASAN: use-after-free Read in __ext4_check_dir_entry
>
> Full report is available here:
> https://ci.syzbot.org/series/5bf0e2fa-2e68-4532-8396-4568879b2788
>
> ***
>
> KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
>
> tree:      torvalds
> URL:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
> arch:      amd64
> compiler:  Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:
> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
> syz repro:
> https://ci.syzbot.org/findings/b0854918-13f9-49dd-ab30-12154f0debe2/syz_repro
>
> loop0: lost filesystem error report for type 5 error -117
> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000
> r/w without journal. Quota mode: none.
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in ext4_dirent_get_data_len
> fs/ext4/ext4.h:4069 [inline]
> BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4096
> [inline]
> BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x65a/0xc40
> fs/ext4/dir.c:96
> Read of size 1 at addr ffff8881022db7f5 by task syz.0.23/5815
>
> CPU: 1 UID: 0 PID: 5815 Comm: syz.0.23 Not tainted syzkaller #0
> PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>  __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
>  ext4_check_all_de+0x66/0x150 fs/ext4/dir.c:657
>  ext4_convert_inline_data_nolock+0x1b7/0x990 fs/ext4/inline.c:1121
>  ext4_try_add_inline_entry+0x604/0x8e0 fs/ext4/inline.c:1247
>  __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
>  ext4_add_entry fs/ext4/namei.c:2613 [inline]
>  ext4_mkdir+0x5e5/0xce0 fs/ext4/namei.c:3175
>  vfs_mkdir+0x413/0x630 fs/namei.c:5271
>  filename_mkdirat+0x285/0x510 fs/namei.c:5304
>  __do_sys_mkdirat fs/namei.c:5325 [inline]
>  __se_sys_mkdirat+0x35/0x150 fs/namei.c:5322
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f669359bcc7
> Code: 00 66 90 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 db f7 ff
> ff 66 2e 0f 1f 84 00 00 00 00 00 90 b8 02 01 00 00 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffd42381d38 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
> RAX: ffffffffffffffda RBX: 00007ffd42381dc0 RCX: 00007f669359bcc7
> RDX: 00000000000001ff RSI: 0000200000001200 RDI: 00000000ffffff9c
> RBP: 00002000000024c0 R08: 0000200000000240 R09: 0000000000000000
> R10: 00002000000024c0 R11: 0000000000000246 R12: 0000200000001200
> R13: 00007ffd42381d80 R14: 0000000000000000 R15: 0000000000000000
>  </TASK>
>
> Allocated by task 5066:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>  __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5420
>  kmalloc_noprof include/linux/slab.h:950 [inline]
>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>  kernfs_get_open_node fs/kernfs/file.c:543 [inline]
>  kernfs_fop_open+0x862/0xda0 fs/kernfs/file.c:718
>  do_dentry_open+0x822/0x13a0 fs/open.c:947
>  vfs_open+0x3b/0x340 fs/open.c:1079
>  do_open fs/namei.c:4699 [inline]
>  path_openat+0x2e08/0x3860 fs/namei.c:4858
>  do_file_open+0x23e/0x4a0 fs/namei.c:4887
>  do_sys_openat2+0x113/0x200 fs/open.c:1364
>  do_sys_open fs/open.c:1370 [inline]
>  __do_sys_openat fs/open.c:1386 [inline]
>  __se_sys_openat fs/open.c:1381 [inline]
>  __x64_sys_openat+0x138/0x170 fs/open.c:1381
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Last potentially related work creation:
>  kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
>  kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
>  kvfree_call_rcu+0x100/0x430 mm/slab_common.c:1970
>  kernfs_unlink_open_file+0x3fe/0x4b0 fs/kernfs/file.c:604
>  kernfs_fop_release+0x2eb/0x440 fs/kernfs/file.c:783
>  __fput+0x44f/0xa60 fs/file_table.c:510
>  fput_close_sync+0x11f/0x240 fs/file_table.c:615
>  __do_sys_close fs/open.c:1507 [inline]
>  __se_sys_close fs/open.c:1492 [inline]
>  __x64_sys_close+0x7e/0x110 fs/open.c:1492
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> The buggy address belongs to the object at ffff8881022db700
>  which belongs to the cache kmalloc-128 of size 128
> The buggy address is located 117 bytes to the right of
>  allocated 128-byte region [ffff8881022db700, ffff8881022db780)
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1022db
> flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
> page_type: f5(slab)
> raw: 017ff00000000000 ffff888100041a00 dead000000000100 dead000000000122
> raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 0, migratetype Unmovable, gfp_mask
> 0xd2000(__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 0,
> tgid 0 (swapper/0), ts 2408938923, free_ts 0
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>  prep_new_page mm/page_alloc.c:1861 [inline]
>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>  alloc_slab_page mm/slub.c:3278 [inline]
>  allocate_slab+0x77/0x660 mm/slub.c:3467
>  new_slab mm/slub.c:3525 [inline]
>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>  refill_sheaf mm/slub.c:2816 [inline]
>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>  alloc_from_pcs mm/slub.c:4750 [inline]
>  slab_alloc_node mm/slub.c:4884 [inline]
>  __do_kmalloc_node mm/slub.c:5295 [inline]
>  __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
>  kmalloc_noprof include/linux/slab.h:954 [inline]
>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>  __alloc_empty_sheaf mm/slub.c:2768 [inline]
>  alloc_empty_sheaf mm/slub.c:2783 [inline]
>  __pcs_replace_empty_main+0x2df/0x720 mm/slub.c:4647
>  alloc_from_pcs mm/slub.c:4750 [inline]
>  slab_alloc_node mm/slub.c:4884 [inline]
>  kmem_cache_alloc_noprof+0x37d/0x650 mm/slub.c:4906
>  dup_fd+0x55/0xb40 fs/file.c:390
>  copy_files+0xc8/0x120 kernel/fork.c:1639
>  copy_process+0x1d94/0x4440 kernel/fork.c:2252
>  kernel_clone+0x2d7/0x940 kernel/fork.c:2722
>  user_mode_thread+0x110/0x180 kernel/fork.c:2798
>  rest_init+0x23/0x300 init/main.c:727
>  start_kernel+0x38a/0x3e0 init/main.c:1220
> page_owner free stack trace missing
>
> Memory state around the buggy address:
>  ffff8881022db680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff8881022db700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffff8881022db780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>                                                              ^
>  ffff8881022db800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff8881022db880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ==================================================================
>
>
> ***
>
> KASAN: slab-out-of-bounds Read in ext4_inlinedir_to_tree
>
> tree:      torvalds
> URL:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
> arch:      amd64
> compiler:  Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:
> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
> syz repro:
> https://ci.syzbot.org/findings/2dff870b-f382-4c93-8d8d-b2291d921224/syz_repro
>
> loop1: lost filesystem error report for type 5 error -117
> EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000
> r/w without journal. Quota mode: none.
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4095
> [inline]
> BUG: KASAN: slab-out-of-bounds in ext4_inlinedir_to_tree+0xda5/0x10d0
> fs/ext4/inline.c:1335
> Read of size 2 at addr ffff888115a3183c by task syz.1.18/5839
>
> CPU: 1 UID: 0 PID: 5839 Comm: syz.1.18 Not tainted syzkaller #0
> PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  ext4_dir_entry_len fs/ext4/ext4.h:4095 [inline]
>  ext4_inlinedir_to_tree+0xda5/0x10d0 fs/ext4/inline.c:1335
>  ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
>  ext4_dx_readdir fs/ext4/dir.c:600 [inline]
>  ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
>  iterate_dir+0x399/0x570 fs/readdir.c:110
>  __do_sys_getdents64 fs/readdir.c:399 [inline]
>  __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f3e02b9ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f3e03ad5028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
> RAX: ffffffffffffffda RBX: 00007f3e02e15fa0 RCX: 00007f3e02b9ce59
> RDX: 0000000000001000 RSI: 0000200000000f80 RDI: 0000000000000004
> RBP: 00007f3e02c32d6f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f3e02e16038 R14: 00007f3e02e15fa0 R15: 00007ffcaa902298
>  </TASK>
>
> Allocated by task 5839:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>  __do_kmalloc_node mm/slub.c:5296 [inline]
>  __kmalloc_noprof+0x35c/0x760 mm/slub.c:5308
>  kmalloc_noprof include/linux/slab.h:954 [inline]
>  ext4_inlinedir_to_tree+0x312/0x10d0 fs/ext4/inline.c:1292
>  ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
>  ext4_dx_readdir fs/ext4/dir.c:600 [inline]
>  ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
>  iterate_dir+0x399/0x570 fs/readdir.c:110
>  __do_sys_getdents64 fs/readdir.c:399 [inline]
>  __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> The buggy address belongs to the object at ffff888115a31800
>  which belongs to the cache kmalloc-64 of size 64
> The buggy address is located 0 bytes to the right of
>  allocated 60-byte region [ffff888115a31800, ffff888115a3183c)
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x115a31
> flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
> page_type: f5(slab)
> raw: 017ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
> raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 0, migratetype Unmovable, gfp_mask
> 0xd2c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
> pid 5051, tgid 5051 (acpid), ts 27203740677, free_ts 27201732767
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>  prep_new_page mm/page_alloc.c:1861 [inline]
>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>  alloc_slab_page mm/slub.c:3278 [inline]
>  allocate_slab+0x77/0x660 mm/slub.c:3467
>  new_slab mm/slub.c:3525 [inline]
>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>  refill_sheaf mm/slub.c:2816 [inline]
>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>  alloc_from_pcs mm/slub.c:4750 [inline]
>  slab_alloc_node mm/slub.c:4884 [inline]
>  __do_kmalloc_node mm/slub.c:5295 [inline]
>  __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
>  kmalloc_noprof include/linux/slab.h:954 [inline]
>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>  tomoyo_get_name+0x20c/0x590 security/tomoyo/memory.c:173
>  tomoyo_parse_name_union+0xd9/0x130 security/tomoyo/util.c:260
>  tomoyo_update_path_acl security/tomoyo/file.c:399 [inline]
>  tomoyo_write_file+0x3a6/0xc50 security/tomoyo/file.c:1027
>  tomoyo_write_domain2 security/tomoyo/common.c:1160 [inline]
>  tomoyo_add_entry security/tomoyo/common.c:2177 [inline]
>  tomoyo_supervisor+0x1208/0x1570 security/tomoyo/common.c:2238
>  tomoyo_audit_path_log security/tomoyo/file.c:169 [inline]
>  tomoyo_path_permission+0x25a/0x380 security/tomoyo/file.c:592
>  tomoyo_check_open_permission+0x2b2/0x470 security/tomoyo/file.c:782
>  security_file_open+0xa9/0x240 security/security.c:2739
>  do_dentry_open+0x4a8/0x13a0 fs/open.c:924
>  vfs_open+0x3b/0x340 fs/open.c:1079
> page last free pid 15 tgid 15 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  __free_pages_prepare mm/page_alloc.c:1397 [inline]
>  __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
>  __tlb_remove_table_free mm/mmu_gather.c:228 [inline]
>  tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:291
>  rcu_do_batch kernel/rcu/tree.c:2617 [inline]
>  rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
>  handle_softirqs+0x22a/0x840 kernel/softirq.c:622
>  run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
>  smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>
> Memory state around the buggy address:
>  ffff888115a31700: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>  ffff888115a31780: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
> >ffff888115a31800: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
>                                         ^
>  ffff888115a31880: 00 00 00 00 00 00 02 fc fc fc fc fc fc fc fc fc
>  ffff888115a31900: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ==================================================================
>
>
> ***
>
> KASAN: slab-use-after-free Read in __ext4_check_dir_entry
>
> tree:      torvalds
> URL:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
> arch:      amd64
> compiler:  Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:
> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
> syz repro:
> https://ci.syzbot.org/findings/f1d48ea1-6e87-4d64-9c13-8bf8aed109fc/syz_repro
>
> loop0: lost filesystem error report for type 5 error -117
> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000
> r/w without journal. Quota mode: none.
> ==================================================================
> BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len
> fs/ext4/ext4.h:4069 [inline]
> BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096
> [inline]
> BUG: KASAN: slab-use-after-free in __ext4_check_dir_entry+0x65a/0xc40
> fs/ext4/dir.c:96
> Read of size 1 at addr ffff888114d8c045 by task syz.0.20/5821
>
> CPU: 1 UID: 0 PID: 5821 Comm: syz.0.20 Not tainted syzkaller #0
> PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>  __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
>  ext4_find_dest_de+0x136/0x770 fs/ext4/namei.c:2203
>  ext4_add_dirent_to_inline+0xcf/0x430 fs/ext4/inline.c:984
>  ext4_try_add_inline_entry+0x235/0x8e0 fs/ext4/inline.c:1213
>  __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
>  ext4_add_entry fs/ext4/namei.c:2613 [inline]
>  ext4_add_nondir+0x111/0x310 fs/ext4/namei.c:2936
>  ext4_create+0x2e9/0x470 fs/ext4/namei.c:2982
>  lookup_open fs/namei.c:4511 [inline]
>  open_last_lookups fs/namei.c:4611 [inline]
>  path_openat+0x1395/0x3860 fs/namei.c:4855
>  do_file_open+0x23e/0x4a0 fs/namei.c:4887
>  do_sys_openat2+0x113/0x200 fs/open.c:1364
>  do_sys_open fs/open.c:1370 [inline]
>  __do_sys_openat fs/open.c:1386 [inline]
>  __se_sys_openat fs/open.c:1381 [inline]
>  __x64_sys_openat+0x138/0x170 fs/open.c:1381
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f922219ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f9223137028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 00007f9222415fa0 RCX: 00007f922219ce59
> RDX: 0000000000042042 RSI: 0000200000000080 RDI: 0000000000000004
> RBP: 00007f9222232d6f R08: 0000000000000000 R09: 0000000000000000
> R10: 000000000000014a R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f9222416038 R14: 00007f9222415fa0 R15: 00007ffd01a2d448
>  </TASK>
>
> Allocated by task 5484:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  unpoison_slab_object mm/kasan/common.c:340 [inline]
>  __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
>  kasan_slab_alloc include/linux/kasan.h:253 [inline]
>  slab_post_alloc_hook mm/slub.c:4570 [inline]
>  slab_alloc_node mm/slub.c:4899 [inline]
>  kmem_cache_alloc_node_noprof+0x384/0x690 mm/slub.c:4951
>  kmalloc_reserve net/core/skbuff.c:613 [inline]
>  __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
>  alloc_skb include/linux/skbuff.h:1385 [inline]
>  nlmsg_new include/net/netlink.h:1055 [inline]
>  mpls_netconf_notify_devconf+0x46/0x100 net/mpls/af_mpls.c:1217
>  mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
>  notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
>  call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
>  call_netdevice_notifiers net/core/dev.c:2301 [inline]
>  unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>  process_one_work kernel/workqueue.c:3314 [inline]
>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>
> Freed by task 5484:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
>  poison_slab_object mm/kasan/common.c:253 [inline]
>  __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
>  kasan_slab_free include/linux/kasan.h:235 [inline]
>  slab_free_hook mm/slub.c:2689 [inline]
>  slab_free mm/slub.c:6251 [inline]
>  kfree+0x1c5/0x640 mm/slub.c:6566
>  skb_kfree_head net/core/skbuff.c:1075 [inline]
>  skb_free_head net/core/skbuff.c:1087 [inline]
>  skb_release_data+0x828/0xa60 net/core/skbuff.c:1114
>  skb_release_all net/core/skbuff.c:1189 [inline]
>  __kfree_skb+0x5d/0x210 net/core/skbuff.c:1203
>  netlink_broadcast_filtered+0xe18/0xf20 net/netlink/af_netlink.c:1540
>  nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
>  nlmsg_multicast include/net/netlink.h:1184 [inline]
>  nlmsg_notify+0xf0/0x1a0 net/netlink/af_netlink.c:2598
>  mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
>  notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
>  call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
>  call_netdevice_notifiers net/core/dev.c:2301 [inline]
>  unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>  process_one_work kernel/workqueue.c:3314 [inline]
>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>
> The buggy address belongs to the object at ffff888114d8c000
>  which belongs to the cache skbuff_small_head of size 704
> The buggy address is located 69 bytes inside of
>  freed 704-byte region [ffff888114d8c000, ffff888114d8c2c0)
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x114d8c
> head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
> flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
> page_type: f5(slab)
> raw: 017ff00000000040 ffff888160416b40 dead000000000100 dead000000000122
> raw: 0000000000000000 0000000800120012 00000000f5000000 0000000000000000
> head: 017ff00000000040 ffff888160416b40 dead000000000100 dead000000000122
> head: 0000000000000000 0000000800120012 00000000f5000000 0000000000000000
> head: 017ff00000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff
> head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 2, migratetype Unmovable, gfp_mask
> 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
> pid 5484, tgid 5484 (kworker/u8:2), ts 72573003529, free_ts 72546506446
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>  prep_new_page mm/page_alloc.c:1861 [inline]
>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>  alloc_slab_page mm/slub.c:3278 [inline]
>  allocate_slab+0x77/0x660 mm/slub.c:3467
>  new_slab mm/slub.c:3525 [inline]
>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>  refill_sheaf mm/slub.c:2816 [inline]
>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>  alloc_from_pcs mm/slub.c:4750 [inline]
>  slab_alloc_node mm/slub.c:4884 [inline]
>  kmem_cache_alloc_node_noprof+0x441/0x690 mm/slub.c:4951
>  kmalloc_reserve net/core/skbuff.c:613 [inline]
>  __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713
>  alloc_skb include/linux/skbuff.h:1385 [inline]
>  nlmsg_new include/net/netlink.h:1055 [inline]
>  mpls_netconf_notify_devconf+0x46/0x100 net/mpls/af_mpls.c:1217
>  mpls_dev_notify+0xb2d/0xd10 net/mpls/af_mpls.c:1691
>  notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
>  call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
>  call_netdevice_notifiers net/core/dev.c:2301 [inline]
>  unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>  process_one_work kernel/workqueue.c:3314 [inline]
>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
> page last free pid 5484 tgid 5484 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  __free_pages_prepare mm/page_alloc.c:1397 [inline]
>  __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
>  stack_depot_save_flags+0x40e/0x810 lib/stackdepot.c:735
>  kasan_save_stack mm/kasan/common.c:58 [inline]
>  kasan_save_track+0x4f/0x80 mm/kasan/common.c:78
>  unpoison_slab_object mm/kasan/common.c:340 [inline]
>  __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
>  kasan_slab_alloc include/linux/kasan.h:253 [inline]
>  slab_post_alloc_hook mm/slub.c:4570 [inline]
>  slab_alloc_node mm/slub.c:4899 [inline]
>  kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4906
>  kmem_alloc_batch lib/debugobjects.c:371 [inline]
>  fill_pool+0x156/0x580 lib/debugobjects.c:420
>  debug_objects_fill_pool lib/debugobjects.c:752 [inline]
>  debug_object_activate+0x4a3/0x580 lib/debugobjects.c:841
>  debug_rcu_head_queue kernel/rcu/rcu.h:236 [inline]
>  __call_rcu_common kernel/rcu/tree.c:3116 [inline]
>  call_rcu+0x43/0x890 kernel/rcu/tree.c:3251
>  kernfs_put+0x259/0x520 fs/kernfs/dir.c:618
>  kernfs_remove_by_name_ns+0xc8/0x140 fs/kernfs/dir.c:1799
>  device_remove_class_symlinks+0x178/0x190 drivers/base/core.c:3479
>  device_del+0x400/0x8f0 drivers/base/core.c:3881
>  unregister_netdevice_many_notify+0x1d5f/0x22c0 net/core/dev.c:12456
>  ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>  ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>  cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>  process_one_work kernel/workqueue.c:3314 [inline]
>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>
> Memory state around the buggy address:
>  ffff888114d8bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff888114d8bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffff888114d8c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                            ^
>  ffff888114d8c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff888114d8c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> ***
>
> KASAN: slab-use-after-free Read in ext4_inlinedir_to_tree
>
> tree:      torvalds
> URL:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
> arch:      amd64
> compiler:  Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:
> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
> syz repro:
> https://ci.syzbot.org/findings/f42da242-e16e-4f10-bf25-0bd7e192d989/syz_repro
>
> loop0: lost filesystem error report for type 5 error -117
> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000
> r/w without journal. Quota mode: none.
> ==================================================================
> BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len
> fs/ext4/ext4.h:4069 [inline]
> BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096
> [inline]
> BUG: KASAN: slab-use-after-free in ext4_inlinedir_to_tree+0x94c/0x10d0
> fs/ext4/inline.c:1335
> Read of size 1 at addr ffff88816fee8825 by task syz.0.20/5867
>
> CPU: 1 UID: 0 PID: 5867 Comm: syz.0.20 Not tainted syzkaller #0
> PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>  ext4_inlinedir_to_tree+0x94c/0x10d0 fs/ext4/inline.c:1335
>  ext4_htree_fill_tree+0x517/0x1230 fs/ext4/namei.c:1182
>  ext4_dx_readdir fs/ext4/dir.c:600 [inline]
>  ext4_readdir+0x2db4/0x3640 fs/ext4/dir.c:146
>  iterate_dir+0x399/0x570 fs/readdir.c:110
>  __do_sys_getdents fs/readdir.c:319 [inline]
>  __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f010ad9ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f010bc0f028 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
> RAX: ffffffffffffffda RBX: 00007f010b015fa0 RCX: 00007f010ad9ce59
> RDX: 0000000000000054 RSI: 0000000000000000 RDI: 0000000000000004
> RBP: 00007f010ae32d6f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f010b016038 R14: 00007f010b015fa0 R15: 00007ffd93577348
>  </TASK>
>
> Allocated by task 5064:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>  __do_kmalloc_node mm/slub.c:5296 [inline]
>  __kmalloc_noprof+0x35c/0x760 mm/slub.c:5308
>  kmalloc_noprof include/linux/slab.h:954 [inline]
>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>  tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
>  tomoyo_encode+0x28b/0x550 security/tomoyo/realpath.c:80
>  tomoyo_realpath_from_path+0x58d/0x5d0 security/tomoyo/realpath.c:283
>  tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
>  tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
>  security_inode_getattr+0x12b/0x310 security/security.c:1895
>  vfs_getattr fs/stat.c:259 [inline]
>  vfs_fstat fs/stat.c:281 [inline]
>  vfs_fstatat+0xb4/0x170 fs/stat.c:371
>  __do_sys_newfstatat fs/stat.c:538 [inline]
>  __se_sys_newfstatat fs/stat.c:532 [inline]
>  __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Freed by task 5064:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
>  poison_slab_object mm/kasan/common.c:253 [inline]
>  __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
>  kasan_slab_free include/linux/kasan.h:235 [inline]
>  slab_free_hook mm/slub.c:2689 [inline]
>  slab_free mm/slub.c:6251 [inline]
>  kfree+0x1c5/0x640 mm/slub.c:6566
>  tomoyo_path_perm+0x403/0x560 security/tomoyo/file.c:847
>  security_inode_getattr+0x12b/0x310 security/security.c:1895
>  vfs_getattr fs/stat.c:259 [inline]
>  vfs_fstat fs/stat.c:281 [inline]
>  vfs_fstatat+0xb4/0x170 fs/stat.c:371
>  __do_sys_newfstatat fs/stat.c:538 [inline]
>  __se_sys_newfstatat fs/stat.c:532 [inline]
>  __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> The buggy address belongs to the object at ffff88816fee8800
>  which belongs to the cache kmalloc-64 of size 64
> The buggy address is located 37 bytes inside of
>  freed 64-byte region [ffff88816fee8800, ffff88816fee8840)
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16fee8
> flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
> page_type: f5(slab)
> raw: 057ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
> raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 0, migratetype Unmovable, gfp_mask
> 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC),
> pid 1, tgid 1 (swapper/0), ts 21294026082, free_ts 0
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>  prep_new_page mm/page_alloc.c:1861 [inline]
>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>  alloc_slab_page mm/slub.c:3278 [inline]
>  allocate_slab+0x77/0x660 mm/slub.c:3467
>  new_slab mm/slub.c:3525 [inline]
>  refill_objects+0x339/0x3d0 mm/slub.c:7272
>  refill_sheaf mm/slub.c:2816 [inline]
>  __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
>  alloc_from_pcs mm/slub.c:4750 [inline]
>  slab_alloc_node mm/slub.c:4884 [inline]
>  __do_kmalloc_node mm/slub.c:5295 [inline]
>  __kmalloc_noprof+0x474/0x760 mm/slub.c:5308
>  kmalloc_noprof include/linux/slab.h:954 [inline]
>  kzalloc_noprof include/linux/slab.h:1188 [inline]
>  handler_new_ref+0x261/0x9c0 drivers/media/v4l2-core/v4l2-ctrls-core.c:1882
>  v4l2_ctrl_add_handler+0x19f/0x290
> drivers/media/v4l2-core/v4l2-ctrls-core.c:2443
>  vivid_create_controls+0x332d/0x3bd0
> drivers/media/test-drivers/vivid/vivid-ctrls.c:2072
>  vivid_create_instance drivers/media/test-drivers/vivid/vivid-core.c:1933
> [inline]
>  vivid_probe+0x4261/0x72b0
> drivers/media/test-drivers/vivid/vivid-core.c:2095
>  platform_probe+0xf9/0x190 drivers/base/platform.c:1432
>  call_driver_probe drivers/base/dd.c:-1 [inline]
>  really_probe+0x267/0xaf0 drivers/base/dd.c:709
>  __driver_probe_device+0x1ef/0x380 drivers/base/dd.c:871
>  driver_probe_device+0x4f/0x240 drivers/base/dd.c:901
>  __driver_attach+0x34c/0x640 drivers/base/dd.c:1295
> page_owner free stack trace missing
>
> Memory state around the buggy address:
>  ffff88816fee8700: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
>  ffff88816fee8780: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
> >ffff88816fee8800: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>                                ^
>  ffff88816fee8880: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>  ffff88816fee8900: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ==================================================================
>
>
> ***
>
> KASAN: use-after-free Read in __ext4_check_dir_entry
>
> tree:      torvalds
> URL:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
> base:      9716c086c8e8b141d35aa61f2e96a2e83de212a7
> arch:      amd64
> compiler:  Debian clang version 21.1.8
> (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:
> https://ci.syzbot.org/builds/ddf6ee7c-dfa8-4383-b004-10140edc081c/config
> syz repro:
> https://ci.syzbot.org/findings/57c0b75a-8922-4dc1-9a20-ca947564792b/syz_repro
>
> ==================================================================
> BUG: KASAN: use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4069
> [inline]
> BUG: KASAN: use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4096
> [inline]
> BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x65a/0xc40
> fs/ext4/dir.c:96
> Read of size 1 at addr ffff88816be85045 by task syz.2.21/5880
>
> CPU: 1 UID: 0 PID: 5880 Comm: syz.2.21 Not tainted syzkaller #0
> PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  ext4_dirent_get_data_len fs/ext4/ext4.h:4069 [inline]
>  ext4_dir_entry_len fs/ext4/ext4.h:4096 [inline]
>  __ext4_check_dir_entry+0x65a/0xc40 fs/ext4/dir.c:96
>  ext4_find_dest_de+0x136/0x770 fs/ext4/namei.c:2203
>  ext4_add_dirent_to_inline+0xcf/0x430 fs/ext4/inline.c:984
>  ext4_try_add_inline_entry+0x235/0x8e0 fs/ext4/inline.c:1213
>  __ext4_add_entry+0x390/0x1f40 fs/ext4/namei.c:2529
>  ext4_add_entry fs/ext4/namei.c:2613 [inline]
>  ext4_add_nondir+0x111/0x310 fs/ext4/namei.c:2936
>  ext4_create+0x2e9/0x470 fs/ext4/namei.c:2982
>  lookup_open fs/namei.c:4511 [inline]
>  open_last_lookups fs/namei.c:4611 [inline]
>  path_openat+0x1395/0x3860 fs/namei.c:4855
>  do_file_open+0x23e/0x4a0 fs/namei.c:4887
>  do_sys_openat2+0x113/0x200 fs/open.c:1364
>  do_sys_open fs/open.c:1370 [inline]
>  __do_sys_openat fs/open.c:1386 [inline]
>  __se_sys_openat fs/open.c:1381 [inline]
>  __x64_sys_openat+0x138/0x170 fs/open.c:1381
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f5713b9ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fff672b25f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 00007f5713e15fa0 RCX: 00007f5713b9ce59
> RDX: 0000000000042042 RSI: 0000200000000080 RDI: 0000000000000004
> RBP: 00007f5713c32d6f R08: 0000000000000000 R09: 0000000000000000
> R10: 000000000000014a R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f5713e15fac R14: 00007f5713e15fa0 R15: 00007f5713e15fa0
>  </TASK>
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16be85
> flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
> page_type: f0(buddy)
> raw: 057ff00000000000 ffffea0005afa0c8 ffffea0005afa1c8 0000000000000000
> raw: 0000000000000000 0000000000000000 00000000f0000000 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as freed
> page last allocated via order 0, migratetype Unmovable, gfp_mask
> 0xcc0(GFP_KERNEL), pid 5630, tgid 5630 (syz-executor), ts 67290853657,
> free_ts 69321168948
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
>  prep_new_page mm/page_alloc.c:1861 [inline]
>  get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
>  __alloc_pages_noprof+0x10/0x100 mm/page_alloc.c:5255
>  alloc_pages_bulk_noprof+0x5ff/0x7c0 mm/page_alloc.c:5175
>  ___alloc_pages_bulk mm/kasan/shadow.c:345 [inline]
>  __kasan_populate_vmalloc_do mm/kasan/shadow.c:370 [inline]
>  __kasan_populate_vmalloc+0xc1/0x1d0 mm/kasan/shadow.c:424
>  kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
>  alloc_vmap_area+0xd47/0x1480 mm/vmalloc.c:2123
>  __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3226
>  __vmalloc_node_range_noprof+0x36a/0x1750 mm/vmalloc.c:4024
>  vmalloc_user_noprof+0xad/0xe0 mm/vmalloc.c:4218
>  kcov_ioctl+0x55/0x620 kernel/kcov.c:726
>  vfs_ioctl fs/ioctl.c:51 [inline]
>  __do_sys_ioctl fs/ioctl.c:597 [inline]
>  __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> page last free pid 5693 tgid 5693 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  __free_pages_prepare mm/page_alloc.c:1397 [inline]
>  __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
>  kasan_depopulate_vmalloc_pte+0x6d/0x90 mm/kasan/shadow.c:484
>  apply_to_pte_range mm/memory.c:3338 [inline]
>  apply_to_pmd_range mm/memory.c:3382 [inline]
>  apply_to_pud_range mm/memory.c:3418 [inline]
>  apply_to_p4d_range mm/memory.c:3454 [inline]
>  __apply_to_page_range+0xbdc/0x1420 mm/memory.c:3490
>  __kasan_release_vmalloc+0xa2/0xd0 mm/kasan/shadow.c:602
>  kasan_release_vmalloc include/linux/kasan.h:593 [inline]
>  kasan_release_vmalloc_node mm/vmalloc.c:2284 [inline]
>  purge_vmap_node+0x220/0x960 mm/vmalloc.c:2306
>  __purge_vmap_area_lazy+0x779/0xb40 mm/vmalloc.c:2396
>  drain_vmap_area_work+0x27/0x40 mm/vmalloc.c:2430
>  process_one_work kernel/workqueue.c:3314 [inline]
>  process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>  worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>
> Memory state around the buggy address:
>  ffff88816be84f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff88816be84f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffff88816be85000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>                                            ^
>  ffff88816be85080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>  ffff88816be85100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ==================================================================
>
>
> ***
>
> If these findings have caused you to resend the series or submit a
> separate fix, please add the following tag to your commit message:
>   Tested-by: syzbot@syzkaller.appspotmail.com
>
> ---
> This report is generated by a bot. It may contain errors.
> syzbot ci engineers can be reached at syzkaller@googlegroups.com.
>
> To test a patch for this bug, please reply with `#syz test`
> (should be on a separate line).
>
> The patch should be attached to the email.
> Note: arguments like custom git repos and branches are not supported.
>
>

[-- Attachment #1.2: Type: text/html, Size: 49844 bytes --]

[-- Attachment #2: dirdata-syzbot-fix.patch --]
[-- Type: application/octet-stream, Size: 11438 bytes --]

From e3d5c74f1ec0fbefb9a4b9193a474614b98d640a Mon Sep 17 00:00:00 2001
From: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Date: Fri, 19 Jun 2026 09:48:12 -0400
Subject: [PATCH] ext4: fix issues reported by syzbot/CI on the dirdata series

Address the following issues found by automated review of the v2
dirdata patch series:

- dx_get_dx_info() called ext4_dir_entry_len() with dir hardcoded to
  NULL, forcing its blocksize fallback to 4096 regardless of the real
  filesystem blocksize, and never validated that the computed offset
  stayed within the block. Thread the real inode through and reject
  out-of-bounds results.

- get_dx_countlimit() had the same NULL-dir blocksize-fallback bug at
  a separate call site; pass the real inode through there too.

- ext4_dirdata_get() declared a local "dfid" inside the
  EXT4_DIRENT_LUFID branch that shadowed the function's own "dfid"
  output parameter, so the LUFID copy never reached the caller's
  buffer. Rename the local and copy into the real parameter. Also,
  both ext4_dirdata_get() and ext4_dirdata_set() compared offsets
  against the raw on-disk de->rec_len instead of decoding it via
  ext4_rec_len_from_disk(), which is wrong on big-endian hosts and
  mishandles the "0/65535 means full block" sentinel.

- ext4_dirdata_set_lufid() (EXT4_IOC_SET_LUFID) deleted the existing
  directory entry and then tried to re-add it with the new LUFID
  data; if ext4_add_entry() failed, the inode was left with no
  directory entry pointing at it. On failure, attempt to restore the
  original entry, and loudly flag inode corruption if that also
  fails.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
---
 fs/ext4/namei.c | 105 +++++++++++++++++++++++++++++++++++-------------
 1 file changed, 78 insertions(+), 27 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 65c53c08213a..e6f54dba735e 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -412,7 +412,7 @@ static struct dx_countlimit *get_dx_countlimit(struct inode *inode,
 		if (le16_to_cpu(de->rec_len) != (blocksize - rlen))
 			return NULL;
 		/* de->rec_len covers whole dx_root block, calculate actual length */
-		dotdot_rec_len = ext4_dir_entry_len(de, NULL);
+		dotdot_rec_len = ext4_dir_entry_len(de, inode);
 		root = (struct dx_root_info *)(((char *)de + dotdot_rec_len));
 		if (root->reserved_zero ||
 		    root->info_length != sizeof(struct dx_root_info))
@@ -520,13 +520,20 @@ ext4_next_entry(struct ext4_dir_entry_2 *p, unsigned long blocksize)
  * Future: use high four bits of block for coalesce-on-delete flags
  * Mask them off for now.
  */
-static struct dx_root_info *dx_get_dx_info(void *de_buf)
+static struct dx_root_info *dx_get_dx_info(struct inode *dir, void *de_buf)
 {
+	unsigned int blocksize = dir->i_sb->s_blocksize;
+	void *base = de_buf;
+
 	/* get dotdot first */
-	de_buf += ext4_dir_entry_len(de_buf, NULL);
+	de_buf += ext4_dir_entry_len(de_buf, dir);
 
 	/* dx root info is after dotdot entry */
-	de_buf += ext4_dir_entry_len(de_buf, NULL);
+	de_buf += ext4_dir_entry_len(de_buf, dir);
+
+	if (de_buf < base || (char *)de_buf - (char *)base +
+			      sizeof(struct dx_root_info) > blocksize)
+		return ERR_PTR(-EFSCORRUPTED);
 
 	return (struct dx_root_info *)de_buf;
 }
@@ -577,7 +584,9 @@ static inline unsigned dx_root_limit(struct inode *dir,
 	struct dx_root_info *info;
 	unsigned int entry_space;
 
-	info = dx_get_dx_info(dot_de);
+	info = dx_get_dx_info(dir, dot_de);
+	if (IS_ERR(info))
+		return 0;
 	entry_space = dir->i_sb->s_blocksize - ((char *)info - (char *)dot_de) -
 		info->info_length;
 
@@ -793,7 +802,9 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
 	if (IS_ERR(frame->bh))
 		return (struct dx_frame *) frame->bh;
 
-	info = dx_get_dx_info((struct ext4_dir_entry_2 *)frame->bh->b_data);
+	info = dx_get_dx_info(dir, (struct ext4_dir_entry_2 *)frame->bh->b_data);
+	if (IS_ERR(info))
+		goto fail;
 	if (info->hash_version != DX_HASH_TEA &&
 	    info->hash_version != DX_HASH_HALF_MD4 &&
 	    info->hash_version != DX_HASH_LEGACY &&
@@ -938,7 +949,7 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
 	return ret_err;
 }
 
-static void dx_release(struct dx_frame *frames)
+static void dx_release(struct inode *dir, struct dx_frame *frames)
 {
 	struct dx_root_info *info;
 	int i;
@@ -947,7 +958,9 @@ static void dx_release(struct dx_frame *frames)
 	if (frames[0].bh == NULL)
 		return;
 
-	info = dx_get_dx_info((struct ext4_dir_entry_2 *)frames[0].bh->b_data);
+	info = dx_get_dx_info(dir, (struct ext4_dir_entry_2 *)frames[0].bh->b_data);
+	if (IS_ERR(info))
+		return;
 	/* save local copy, "info" may be freed after brelse() */
 	indirect_levels = info->indirect_levels;
 	for (i = 0; i <= indirect_levels; i++) {
@@ -1253,12 +1266,12 @@ int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,
 		    (count && ((hashval & 1) == 0)))
 			break;
 	}
-	dx_release(frames);
+	dx_release(dir, frames);
 	dxtrace(printk(KERN_DEBUG "Fill tree: returned %d entries, "
 		       "next hash: %x\n", count, *next_hash));
 	return count;
 errout:
-	dx_release(frames);
+	dx_release(dir, frames);
 	return (err);
 }
 
@@ -1296,8 +1309,10 @@ unsigned char ext4_dirdata_get(struct ext4_dir_entry_2 *de, struct inode *dir,
 {
 	unsigned char ret = 0;
 	unsigned int data_offset = de->name_len + 1;
+	unsigned int rec_len = ext4_rec_len_from_disk(de->rec_len,
+						       dir->i_sb->s_blocksize);
 
-	if (data_offset > de->rec_len)
+	if (data_offset > rec_len)
 		return ret;
 
 	/* compatibility: hash stored inline after filename (no dirdata) */
@@ -1312,19 +1327,20 @@ unsigned char ext4_dirdata_get(struct ext4_dir_entry_2 *de, struct inode *dir,
 
 	/*  EXT4_DIRENT_* are not expected without flag in i_sb */
 	if (de->file_type & EXT4_DIRENT_LUFID) {
-		struct ext4_dirent_fid *dfid =
+		struct ext4_dirent_fid *disk_fid =
 			(struct ext4_dirent_fid *)(de->name + data_offset);
 		unsigned int dlen;
 
-		if (data_offset + sizeof(dfid->df_header) > de->rec_len)
+		if (data_offset + sizeof(disk_fid->df_header) > rec_len)
 			return ret;
 
-		dlen = dfid->df_header.ddh_length;
-		if (dlen < sizeof(*dfid) || data_offset + dlen > de->rec_len)
+		dlen = disk_fid->df_header.ddh_length;
+		if (dlen < sizeof(*disk_fid) || data_offset + dlen > rec_len)
 			return ret;
 
 		if (dfid) {
-			memcpy(dfid, dfid->df_fid, dfid->df_header.ddh_length);
+			memcpy(dfid, disk_fid->df_fid,
+			       disk_fid->df_header.ddh_length);
 			ret |= EXT4_DIRENT_LUFID;
 		}
 		data_offset += dlen;
@@ -1336,11 +1352,11 @@ unsigned char ext4_dirdata_get(struct ext4_dir_entry_2 *de, struct inode *dir,
 		       (struct ext4_dirent_data_header *)(de->name + data_offset);
 		unsigned int dlen;
 
-		if (data_offset + sizeof(*ddh) > de->rec_len)
+		if (data_offset + sizeof(*ddh) > rec_len)
 			return ret;
 
 		dlen = ddh->ddh_length;
-		if (dlen < sizeof(*ddh) || data_offset + dlen > de->rec_len)
+		if (dlen < sizeof(*ddh) || data_offset + dlen > rec_len)
 			return ret;
 
 		data_offset += dlen;
@@ -1355,7 +1371,7 @@ unsigned char ext4_dirdata_get(struct ext4_dir_entry_2 *de, struct inode *dir,
 		unsigned int dlen;
 
 		dlen = dh->dh_header.ddh_length;
-		if (dlen < sizeof(*dh) || data_offset + dlen > de->rec_len)
+		if (dlen < sizeof(*dh) || data_offset + dlen > rec_len)
 			return ret;
 
 		hinfo->hash = le32_to_cpu(dh->dh_hash.hash);
@@ -1383,12 +1399,14 @@ static void ext4_dirdata_set(struct ext4_dir_entry_2 *de, struct inode *dir,
 {
 	struct dx_hash_info *hinfo = &fname->hinfo;
 	unsigned int data_offset = de->name_len + 1;
+	unsigned int rec_len = ext4_rec_len_from_disk(de->rec_len,
+						       dir->i_sb->s_blocksize);
 
 
 	if (dfid) {
 		unsigned int dlen = dfid->df_header.ddh_length;
 
-		if (data_offset + dlen > de->rec_len) {
+		if (data_offset + dlen > rec_len) {
 			EXT4_ERROR_INODE(dir, "Can not insert FID");
 			return;
 		}
@@ -1406,7 +1424,7 @@ static void ext4_dirdata_set(struct ext4_dir_entry_2 *de, struct inode *dir,
 			struct ext4_dirent_hash *dh =
 			    (struct ext4_dirent_hash *)(de->name + data_offset);
 
-			if (data_offset + sizeof(*dh) > de->rec_len) {
+			if (data_offset + sizeof(*dh) > rec_len) {
 				EXT4_ERROR_INODE(dir, "Can not insert dhash dirdata");
 				return;
 			}
@@ -1418,7 +1436,7 @@ static void ext4_dirdata_set(struct ext4_dir_entry_2 *de, struct inode *dir,
 		} else {
 			/* Compatibility: store hash inline after filename */
 			if (data_offset + sizeof(struct ext4_dir_entry_hash) >
-								de-> rec_len) {
+								rec_len) {
 				EXT4_ERROR_INODE(dir, "Can not insert dhash");
 				return;
 			}
@@ -1906,7 +1924,7 @@ static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
 errout:
 	dxtrace(printk(KERN_DEBUG "%s not found\n", fname->usr_fname->name));
 success:
-	dx_release(frames);
+	dx_release(dir, frames);
 	return bh;
 }
 
@@ -2425,7 +2443,12 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 				     blocksize);
 
 	/* initialize hashing info */
-	dx_info = dx_get_dx_info(dot_de);
+	dx_info = dx_get_dx_info(dir, dot_de);
+	if (IS_ERR(dx_info)) {
+		brelse(bh2);
+		brelse(bh);
+		return PTR_ERR(dx_info);
+	}
 	memset(dx_info, 0, sizeof(*dx_info));
 	dx_info->info_length = sizeof(*dx_info);
 	if (ext4_hash_in_dirent(dir))
@@ -2483,7 +2506,7 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 	 */
 	if (retval)
 		ext4_mark_inode_dirty(handle, dir);
-	dx_release(frames);
+	dx_release(dir, frames);
 	brelse(bh2);
 	return retval;
 }
@@ -2759,8 +2782,13 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname,
 			/* Set up root */
 			dx_set_count(entries, 1);
 			dx_set_block(entries + 0, newblock);
-			info = dx_get_dx_info((struct ext4_dir_entry_2 *)
+			info = dx_get_dx_info(dir, (struct ext4_dir_entry_2 *)
 					      frames[0].bh->b_data);
+			if (IS_ERR(info)) {
+				err = PTR_ERR(info);
+				brelse(bh2);
+				goto journal_error;
+			}
 			info->indirect_levels += 1;
 			dxtrace(printk(KERN_DEBUG
 				       "Creating %d level index...\n",
@@ -2788,7 +2816,7 @@ static int ext4_dx_add_entry(handle_t *handle, struct ext4_filename *fname,
 	ext4_std_error(dir->i_sb, err); /* this is a no-op if err == 0 */
 cleanup:
 	brelse(bh);
-	dx_release(frames);
+	dx_release(dir, frames);
 	/* @restart is true means htree-path has been changed, we need to
 	 * repeat dx_probe() to find out valid htree-path
 	 */
@@ -4463,6 +4491,29 @@ int ext4_dirdata_set_lufid(struct inode *dir, const char *filename,
 	}
 	EXT4_I(inode)->i_dirdata = old_dirdata;
 
+	if (err) {
+		/*
+		 * The original entry was already removed above and the
+		 * re-add with the new LUFID failed; try to restore the
+		 * original entry so the inode isn't left without any
+		 * directory entry pointing at it.
+		 */
+		struct dentry parent_dentry = { .d_inode = dir };
+		struct dentry orig_dentry = {
+			.d_name = d_name,
+			.d_parent = &parent_dentry,
+			.d_inode = inode,
+		};
+		int rollback_err = ext4_add_entry(handle, &orig_dentry, inode);
+
+		if (rollback_err)
+			EXT4_ERROR_INODE(dir,
+				"Failed to set LUFID on '%.*s' (err=%d) and failed to restore the original directory entry (err=%d); inode %llu may be orphaned",
+				namelen, filename, err, rollback_err,
+				inode->i_ino);
+		goto out_unlock;
+	}
+
 	/* Update inode times */
 	inode_set_ctime_current(dir);
 	inode_inc_iversion(dir);
-- 
2.43.7

[syzbot ci] Re: Data in direntry (dirdata) feature

[syzbot ci]

syzbot ci has tested the suggested fix patch on top of the following series:

[v2] Data in direntry (dirdata) feature
https://lore.kernel.org/all/20260610152417.13576-1-ablagodarenko@thelustrecollective.com

Patch: https://ci.syzbot.org/jobs/7b048bf9-1956-4726-960c-6439488b701f/patch
Testing results:
* [build 0] Build Patched: passed
* [build 0] Boot test: Patched: passed

Full report is available here:
https://ci.syzbot.org/session/40a7ca8a-ac83-4f97-91a0-233437f73a40

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.

[PATCH v3 00/10] Data in direntry (dirdata) feature

[Artem Blagodarenko]

EXT4 currently stores a hash in the directory entry
(dirent) immediately after the file name to support
simultaneous fscrypt and casefold functionality.

It has been discussed within the EXT4 community that
this hash could instead be stored in dirdata. This
would make it the second (or third, in the case of
64-bit inode counts) user of dirdata.

At the same time, the existing format—where the hash
is placed after the file name—must continue to be
supported. With these patches, EXT4 can handle the
hash in both formats.

The first user of this feature is  LUFID -
Locally Unique File ID.

Support for fscrypt and case-insensitive directories
with dirdata enabled has been verified using a
dedicated xfstest submitted to the xfstests list as
a separate patch.

e2fsprogs support is provided in a separate patches
series.

Changes in v3:
- Fixed issues reported by automated review of v2:
  - dx_get_dx_info() and get_dx_countlimit() called
    ext4_dir_entry_len() with the directory inode
    hardcoded to NULL, forcing its blocksize fallback
    to 4096 regardless of the real filesystem blocksize.
    Both now pass the real inode through, and
    dx_get_dx_info() also rejects results that fall
    outside the directory block.
  - ext4_dirdata_get() declared a local "dfid" that
    shadowed the function's own "dfid" output parameter,
    so a requested LUFID copy never reached the caller's
    buffer. Renamed the local and fixed the copy.
  - ext4_dirdata_get()/ext4_dirdata_set() compared
    offsets against the raw on-disk rec_len instead of
    decoding it via ext4_rec_len_from_disk(), which is
    incorrect on big-endian hosts and mishandles the
    "0/65535 means full block" sentinel. Both now decode
    rec_len once and use the decoded value throughout.
  - EXT4_IOC_SET_LUFID deleted the existing directory
    entry before re-adding it with the new LUFID data;
    if the re-add failed, the inode was left with no
    directory entry at all. It now attempts to restore
    the original entry on failure, and loudly flags
    inode corruption if that also fails.
- syzbot ci tested the fix for these issues; per its
  request, this is being submitted with the corresponding
  Tested-by tag below.
- Rebased onto the latest codebase.

Artem Blagodarenko (10):
  ext4: replace ext4_dir_entry with ext4_dir_entry_2
  ext4: add ext4_dir_entry_is_tail()
  ext4: refactor dx_root to support variable dirent sizes
  ext4: add dirdata format definitions and access helpers
  ext4: preserve dirdata bits in get_dtype()
  ext4: add ext4_dir_entry_len() and harden dirdata parsing
  ext4: rename ext4_dir_rec_len() and clarify dirdata usage
  ext4: dirdata feature
  ext4: add dirdata set/get helpers
  ext4: Add EXT4_IOC_SET_LUFID ioctl for setting LUFID on directory
    entries

 foofile.txt               |   0
 fs/ext4/dir.c             |   9 +-
 fs/ext4/ext4.h            | 205 +++++++++++-
 fs/ext4/inline.c          |  37 ++-
 fs/ext4/ioctl.c           |  62 ++++
 fs/ext4/namei.c           | 650 ++++++++++++++++++++++++++++----------
 fs/ext4/sysfs.c           |   2 +
 include/uapi/linux/ext4.h |  13 +
 8 files changed, 780 insertions(+), 198 deletions(-)
 create mode 100644 foofile.txt

Tested-by: syzbot@syzkaller.appspotmail.com
-- 
2.43.7

[syzbot ci] Re: Data in direntry (dirdata) feature

[syzbot ci]

syzbot ci has tested the following series

[v3] Data in direntry (dirdata) feature
https://lore.kernel.org/all/20260619191022.27008-1-ablagodarenko@thelustrecollective.com
* [PATCH v3 01/10] ext4: replace ext4_dir_entry with ext4_dir_entry_2
* [PATCH v3 02/10] ext4: add ext4_dir_entry_is_tail()
* [PATCH v3 03/10] ext4: refactor dx_root to support variable dirent sizes
* [PATCH v3 04/10] ext4: add dirdata format definitions and access helpers
* [PATCH v3 05/10] ext4: preserve dirdata bits in get_dtype()
* [PATCH v3 06/10] ext4: add ext4_dir_entry_len() and harden dirdata parsing
* [PATCH v3 07/10] ext4: rename ext4_dir_rec_len() and clarify dirdata usage
* [PATCH v3 08/10] ext4: dirdata feature
* [PATCH v3 09/10] ext4: add dirdata set/get helpers
* [PATCH v3 10/10] ext4: Add EXT4_IOC_SET_LUFID ioctl for setting LUFID on directory entries

and found the following issues:
* KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
* KASAN: slab-out-of-bounds Read in ext4_inlinedir_to_tree
* KASAN: slab-use-after-free Read in __ext4_check_dir_entry
* KASAN: slab-use-after-free Read in ext4_inlinedir_to_tree
* KASAN: use-after-free Read in __ext4_check_dir_entry

Full report is available here:
https://ci.syzbot.org/series/a3c6e513-a6eb-4583-86f6-89176398b397

***

KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      08c7183f5b9ffe4408e74fff848a4cc2105361d4
arch:      amd64
compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
config:    https://ci.syzbot.org/builds/0efdb868-daeb-4649-9bcb-5af41d993e73/config
syz repro: https://ci.syzbot.org/findings/ec557d64-7b60-46c9-a0eb-feaa7a3eb2cd/syz_repro

loop0: lost filesystem error report for type 5 error -117
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_dirent_get_data_len fs/ext4/ext4.h:4156 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4183 [inline]
BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x659/0xbe0 fs/ext4/dir.c:96
Read of size 1 at addr ffff88816e86bcd9 by task syz.0.21/5783

CPU: 1 UID: 0 PID: 5783 Comm: syz.0.21 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4156 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4183 [inline]
 __ext4_check_dir_entry+0x659/0xbe0 fs/ext4/dir.c:96
 ext4_check_all_de+0x6a/0x140 fs/ext4/dir.c:657
 ext4_convert_inline_data_nolock+0x1b7/0x980 fs/ext4/inline.c:1121
 ext4_try_add_inline_entry+0x5cc/0x8a0 fs/ext4/inline.c:1247
 __ext4_add_entry+0x385/0x3470 fs/ext4/namei.c:2552
 ext4_add_entry fs/ext4/namei.c:2636 [inline]
 ext4_mkdir+0x5f3/0xd30 fs/ext4/namei.c:3203
 vfs_mkdir+0x406/0x620 fs/namei.c:5272
 filename_mkdirat+0x285/0x510 fs/namei.c:5305
 __do_sys_mkdirat fs/namei.c:5326 [inline]
 __se_sys_mkdirat+0x35/0x150 fs/namei.c:5323
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb4c839ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd4b254a88 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fb4c8615fa0 RCX: 00007fb4c839ce59
RDX: 0000000000000037 RSI: 0000200000000380 RDI: 0000000000000004
RBP: 00007fb4c8432e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb4c8615fac R14: 00007fb4c8615fa0 R15: 00007fb4c8615fa0
 </TASK>

Allocated by task 5056:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x318/0x660 mm/slub.c:5451
 _kmalloc_noprof include/linux/slab.h:969 [inline]
 _kzalloc_noprof include/linux/slab.h:1286 [inline]
 kernfs_get_open_node fs/kernfs/file.c:536 [inline]
 kernfs_fop_open+0x7e6/0xce0 fs/kernfs/file.c:711
 do_dentry_open+0x816/0x1380 fs/open.c:947
 vfs_open+0x3b/0x340 fs/open.c:1079
 do_open fs/namei.c:4700 [inline]
 path_openat+0x2e44/0x3830 fs/namei.c:4859
 do_file_open+0x23e/0x4a0 fs/namei.c:4888
 do_sys_openat2+0x115/0x200 fs/open.c:1395
 do_sys_open fs/open.c:1401 [inline]
 __do_sys_openat fs/open.c:1417 [inline]
 __se_sys_openat fs/open.c:1412 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1412
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88816e86bc00
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 89 bytes to the right of
 allocated 128-byte region [ffff88816e86bc00, ffff88816e86bc80)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88816e86bf00 pfn:0x16e86b
flags: 0x57ff00000000200(workingset|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000200 ffff888100041a00 ffff888160400648 ffff888160400648
raw: ffff88816e86bf00 000000080010000f 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5056, tgid 5056 (udevd), ts 53238350188, free_ts 53091667410
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x24ae/0x2530 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3289 [inline]
 allocate_slab+0x74/0x5d0 mm/slub.c:3404
 new_slab mm/slub.c:3447 [inline]
 refill_objects+0x328/0x3c0 mm/slub.c:7241
 refill_sheaf mm/slub.c:2827 [inline]
 __pcs_replace_empty_main+0x2e0/0x6b0 mm/slub.c:4692
 alloc_from_pcs mm/slub.c:4790 [inline]
 slab_alloc_node mm/slub.c:4924 [inline]
 __kmalloc_cache_noprof+0x388/0x660 mm/slub.c:5446
 _kmalloc_noprof include/linux/slab.h:969 [inline]
 _kzalloc_noprof include/linux/slab.h:1286 [inline]
 kernfs_get_open_node fs/kernfs/file.c:536 [inline]
 kernfs_fop_open+0x7e6/0xce0 fs/kernfs/file.c:711
 do_dentry_open+0x816/0x1380 fs/open.c:947
 vfs_open+0x3b/0x340 fs/open.c:1079
 do_open fs/namei.c:4700 [inline]
 path_openat+0x2e44/0x3830 fs/namei.c:4859
 do_file_open+0x23e/0x4a0 fs/namei.c:4888
 do_sys_openat2+0x115/0x200 fs/open.c:1395
 do_sys_open fs/open.c:1401 [inline]
 __do_sys_openat fs/open.c:1417 [inline]
 __se_sys_openat fs/open.c:1412 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1412
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 23 tgid 23 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1397 [inline]
 __free_frozen_pages+0xc0d/0xd20 mm/page_alloc.c:2938
 __tlb_remove_table_free mm/mmu_gather.c:228 [inline]
 tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:291
 rcu_do_batch kernel/rcu/tree.c:2645 [inline]
 rcu_core+0x78b/0x10a0 kernel/rcu/tree.c:2897
 handle_softirqs+0x225/0x840 kernel/softirq.c:622
 run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
 smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff88816e86bb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88816e86bc00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88816e86bc80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                    ^
 ffff88816e86bd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88816e86bd80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: slab-out-of-bounds Read in ext4_inlinedir_to_tree

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      08c7183f5b9ffe4408e74fff848a4cc2105361d4
arch:      amd64
compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
config:    https://ci.syzbot.org/builds/0efdb868-daeb-4649-9bcb-5af41d993e73/config
syz repro: https://ci.syzbot.org/findings/bb78d414-4cff-400b-aaf6-76d450b12cda/syz_repro

==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4182 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_inlinedir_to_tree+0xd95/0x10a0 fs/ext4/inline.c:1335
Read of size 2 at addr ffff88816f219a3c by task syz.1.18/5830

CPU: 1 UID: 0 PID: 5830 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dir_entry_len fs/ext4/ext4.h:4182 [inline]
 ext4_inlinedir_to_tree+0xd95/0x10a0 fs/ext4/inline.c:1335
 ext4_htree_fill_tree+0x4c9/0x2480 fs/ext4/namei.c:1195
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2e2a/0x3720 fs/ext4/dir.c:146
 iterate_dir+0x2e2/0x4d0 fs/readdir.c:110
 __do_sys_getdents fs/readdir.c:319 [inline]
 __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe51459ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe515527028 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007fe514815fa0 RCX: 00007fe51459ce59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007fe514632e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe514816038 R14: 00007fe514815fa0 R15: 00007fffd9b381d8
 </TASK>

Allocated by task 5830:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5334 [inline]
 __kmalloc_noprof+0x358/0x750 mm/slub.c:5347
 _kmalloc_noprof include/linux/slab.h:973 [inline]
 ext4_inlinedir_to_tree+0x2ec/0x10a0 fs/ext4/inline.c:1292
 ext4_htree_fill_tree+0x4c9/0x2480 fs/ext4/namei.c:1195
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2e2a/0x3720 fs/ext4/dir.c:146
 iterate_dir+0x2e2/0x4d0 fs/readdir.c:110
 __do_sys_getdents fs/readdir.c:319 [inline]
 __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88816f219a00
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes to the right of
 allocated 60-byte region [ffff88816f219a00, ffff88816f219a3c)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16f219
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 10138712683, free_ts 10137977139
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x24ae/0x2530 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3289 [inline]
 allocate_slab+0x74/0x5d0 mm/slub.c:3404
 new_slab mm/slub.c:3447 [inline]
 refill_objects+0x328/0x3c0 mm/slub.c:7241
 refill_sheaf mm/slub.c:2827 [inline]
 __pcs_replace_empty_main+0x2e0/0x6b0 mm/slub.c:4692
 alloc_from_pcs mm/slub.c:4790 [inline]
 slab_alloc_node mm/slub.c:4924 [inline]
 __do_kmalloc_node mm/slub.c:5333 [inline]
 __kmalloc_noprof+0x464/0x750 mm/slub.c:5347
 _kmalloc_noprof include/linux/slab.h:973 [inline]
 _kzalloc_noprof include/linux/slab.h:1286 [inline]
 kobject_get_path+0xc5/0x2f0 lib/kobject.c:161
 kobject_uevent_env+0x29e/0x9e0 lib/kobject_uevent.c:548
 device_add+0x544/0xb80 drivers/base/core.c:3738
 scsi_add_host_with_dma+0x5db/0xd00 drivers/scsi/hosts.c:287
 ata_scsi_add_hosts+0x29b/0x4b0 drivers/ata/libata-scsi.c:4659
 ata_host_register+0x1c5/0x7d0 drivers/ata/libata-core.c:6131
 ata_host_activate+0x33c/0x3c0 drivers/ata/libata-core.c:6234
 ahci_init_one+0x1afa/0x22b0 drivers/ata/ahci.c:3090
 local_pci_probe drivers/pci/pci-driver.c:332 [inline]
 pci_call_probe drivers/pci/pci-driver.c:394 [inline]
 __pci_device_probe drivers/pci/pci-driver.c:455 [inline]
 pci_device_probe+0x431/0xc90 drivers/pci/pci-driver.c:489
page last free pid 36 tgid 36 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1397 [inline]
 __free_frozen_pages+0xc0d/0xd20 mm/page_alloc.c:2938
 __kasan_populate_vmalloc_do mm/kasan/shadow.c:393 [inline]
 __kasan_populate_vmalloc+0x1a8/0x1c0 mm/kasan/shadow.c:424
 kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
 alloc_vmap_area+0xd1a/0x1420 mm/vmalloc.c:2123
 __get_vm_area_node+0x1f2/0x300 mm/vmalloc.c:3226
 __vmalloc_node_range_noprof+0x358/0x1730 mm/vmalloc.c:4024
 __vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4124
 alloc_thread_stack_node kernel/fork.c:358 [inline]
 dup_task_struct+0x28e/0x850 kernel/fork.c:928
 copy_process+0x81b/0x42e0 kernel/fork.c:2109
 kernel_clone+0x2d7/0x940 kernel/fork.c:2745
 user_mode_thread+0x110/0x180 kernel/fork.c:2821
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff88816f219900: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
 ffff88816f219980: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88816f219a00: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
                                        ^
 ffff88816f219a80: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88816f219b00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: slab-use-after-free Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      08c7183f5b9ffe4408e74fff848a4cc2105361d4
arch:      amd64
compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
config:    https://ci.syzbot.org/builds/0efdb868-daeb-4649-9bcb-5af41d993e73/config
syz repro: https://ci.syzbot.org/findings/f322e293-7a3f-469a-ae1f-677c84eb4c0f/syz_repro

==================================================================
BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4156 [inline]
BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4183 [inline]
BUG: KASAN: slab-use-after-free in __ext4_check_dir_entry+0x659/0xbe0 fs/ext4/dir.c:96
Read of size 1 at addr ffff888103e89c1d by task syz.2.19/5867

CPU: 0 UID: 0 PID: 5867 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4156 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4183 [inline]
 __ext4_check_dir_entry+0x659/0xbe0 fs/ext4/dir.c:96
 ext4_check_all_de+0x6a/0x140 fs/ext4/dir.c:657
 ext4_convert_inline_data_nolock+0x1b7/0x980 fs/ext4/inline.c:1121
 ext4_try_add_inline_entry+0x5cc/0x8a0 fs/ext4/inline.c:1247
 __ext4_add_entry+0x385/0x3470 fs/ext4/namei.c:2552
 ext4_add_entry fs/ext4/namei.c:2636 [inline]
 ext4_mkdir+0x5f3/0xd30 fs/ext4/namei.c:3203
 vfs_mkdir+0x406/0x620 fs/namei.c:5272
 filename_mkdirat+0x285/0x510 fs/namei.c:5305
 __do_sys_mkdirat fs/namei.c:5326 [inline]
 __se_sys_mkdirat+0x35/0x150 fs/namei.c:5323
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb01d39ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb01e269028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fb01d615fa0 RCX: 00007fb01d39ce59
RDX: 0000000000000037 RSI: 0000200000000380 RDI: 0000000000000004
RBP: 00007fb01d432e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb01d616038 R14: 00007fb01d615fa0 R15: 00007ffdec822cc8
 </TASK>

Allocated by task 5630:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x318/0x660 mm/slub.c:5451
 _kmalloc_noprof include/linux/slab.h:969 [inline]
 __hw_addr_create+0x62/0x240 net/core/dev_addr_lists.c:69
 __hw_addr_add_ex+0x1ce/0x520 net/core/dev_addr_lists.c:127
 __hw_addr_add net/core/dev_addr_lists.c:144 [inline]
 dev_addr_init+0x15a/0x240 net/core/dev_addr_lists.c:696
 alloc_netdev_mqs+0x2b4/0x1270 net/core/dev.c:12064
 __ip_tunnel_create+0x348/0x560 net/ipv4/ip_tunnel.c:255
 ip_tunnel_init_net+0x2ea/0x810 net/ipv4/ip_tunnel.c:1150
 ops_init+0x35d/0x5d0 net/core/net_namespace.c:137
 setup_net+0x118/0x350 net/core/net_namespace.c:446
 copy_net_ns+0x4f9/0x720 net/core/net_namespace.c:579
 create_new_namespaces+0x3f0/0x6b0 kernel/nsproxy.c:132
 unshare_nsproxy_namespaces+0x149/0x190 kernel/nsproxy.c:234
 ksys_unshare+0x57d/0xa00 kernel/fork.c:3266
 __do_sys_unshare kernel/fork.c:3340 [inline]
 __se_sys_unshare kernel/fork.c:3338 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 68:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2700 [inline]
 slab_free_freelist_hook mm/slub.c:2729 [inline]
 slab_free_bulk mm/slub.c:6344 [inline]
 kmem_cache_free_bulk+0x30f/0x1180 mm/slub.c:7076
 kfree_bulk include/linux/slab.h:891 [inline]
 kvfree_rcu_bulk+0xc6/0x190 mm/slab_common.c:1502
 kvfree_rcu_drain_ready mm/slab_common.c:1704 [inline]
 kfree_rcu_monitor+0x21a/0x2b0 mm/slab_common.c:1777
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 kvfree_call_rcu+0x100/0x430 mm/slab_common.c:1970
 __hw_addr_flush net/core/dev_addr_lists.c:500 [inline]
 dev_addr_flush+0x16c/0x210 net/core/dev_addr_lists.c:673
 free_netdev+0x26c/0x6e0 net/core/dev.c:12209
 netdev_run_todo+0xf3d/0x10d0 net/core/dev.c:11743
 ops_exit_rtnl_list net/core/net_namespace.c:189 [inline]
 ops_undo_list+0x396/0x8d0 net/core/net_namespace.c:248
 cleanup_net+0x572/0x810 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888103e89c00
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 29 bytes inside of
 freed 128-byte region [ffff888103e89c00, ffff888103e89c80)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x103e89
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000000 ffff888100041a00 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 2773920656, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x24ae/0x2530 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3289 [inline]
 allocate_slab+0x74/0x5d0 mm/slub.c:3404
 new_slab mm/slub.c:3447 [inline]
 refill_objects+0x328/0x3c0 mm/slub.c:7241
 refill_sheaf mm/slub.c:2827 [inline]
 __pcs_replace_empty_main+0x2e0/0x6b0 mm/slub.c:4692
 alloc_from_pcs mm/slub.c:4790 [inline]
 slab_alloc_node mm/slub.c:4924 [inline]
 __do_kmalloc_node mm/slub.c:5333 [inline]
 __kmalloc_noprof+0x464/0x750 mm/slub.c:5347
 _kmalloc_noprof include/linux/slab.h:973 [inline]
 _kzalloc_noprof include/linux/slab.h:1286 [inline]
 __alloc_empty_sheaf+0x24/0x40 mm/slub.c:2774
 alloc_empty_sheaf mm/slub.c:2794 [inline]
 __pcs_replace_empty_main+0x447/0x6b0 mm/slub.c:4687
 alloc_from_pcs mm/slub.c:4790 [inline]
 slab_alloc_node mm/slub.c:4924 [inline]
 kmem_cache_alloc_lru_noprof+0x372/0x640 mm/slub.c:4958
 alloc_inode+0x6a/0x1b0 fs/inode.c:341
 new_inode+0x1f/0x170 fs/inode.c:1177
 debugfs_get_inode fs/debugfs/inode.c:72 [inline]
 debugfs_create_dir+0x68/0x350 fs/debugfs/inode.c:578
 blk_dev_init+0xdf/0x150 block/blk-core.c:1333
 genhd_device_init+0x1c/0x50 block/genhd.c:1002
 do_one_initcall+0x250/0x870 init/main.c:1347
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888103e89b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888103e89b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888103e89c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff888103e89c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888103e89d00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


***

KASAN: slab-use-after-free Read in ext4_inlinedir_to_tree

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      08c7183f5b9ffe4408e74fff848a4cc2105361d4
arch:      amd64
compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
config:    https://ci.syzbot.org/builds/0efdb868-daeb-4649-9bcb-5af41d993e73/config
syz repro: https://ci.syzbot.org/findings/b1e2a550-a6c3-410a-ae53-ca1e5366cc94/syz_repro

loop0: lost filesystem error report for type 5 error -117
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4156 [inline]
BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4183 [inline]
BUG: KASAN: slab-use-after-free in ext4_inlinedir_to_tree+0x8f0/0x10a0 fs/ext4/inline.c:1335
Read of size 1 at addr ffff888111d0149d by task syz.0.19/5801

CPU: 1 UID: 0 PID: 5801 Comm: syz.0.19 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4156 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4183 [inline]
 ext4_inlinedir_to_tree+0x8f0/0x10a0 fs/ext4/inline.c:1335
 ext4_htree_fill_tree+0x4c9/0x2480 fs/ext4/namei.c:1195
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2e2a/0x3720 fs/ext4/dir.c:146
 iterate_dir+0x2e2/0x4d0 fs/readdir.c:110
 __do_sys_getdents fs/readdir.c:319 [inline]
 __se_sys_getdents+0xf1/0x270 fs/readdir.c:304
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6e8459ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffef0bce788 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007f6e84815fa0 RCX: 00007f6e8459ce59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f6e84632e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6e84815fac R14: 00007f6e84815fa0 R15: 00007f6e84815fa0
 </TASK>

Allocated by task 5738:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x318/0x660 mm/slub.c:5451
 _kmalloc_noprof include/linux/slab.h:969 [inline]
 __kthread_create_on_node+0x115/0x3d0 kernel/kthread.c:483
 kthread_create_on_node+0xeb/0x140 kernel/kthread.c:559
 napi_kthread_create net/core/dev.c:1656 [inline]
 netif_napi_add_weight_locked+0x699/0x940 net/core/dev.c:7594
 netif_napi_add_weight include/linux/netdevice.h:2870 [inline]
 netif_napi_add include/linux/netdevice.h:2887 [inline]
 wg_peer_create+0x52d/0x860 drivers/net/wireguard/peer.c:57
 set_peer drivers/net/wireguard/netlink.c:392 [inline]
 wg_set_device_doit+0xf3a/0x2120 drivers/net/wireguard/netlink.c:569
 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
 __sock_sendmsg net/socket.c:790 [inline]
 __sys_sendto+0x408/0x5a0 net/socket.c:2252
 __do_sys_sendto net/socket.c:2259 [inline]
 __se_sys_sendto net/socket.c:2255 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2255
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5738:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2700 [inline]
 slab_free mm/slub.c:6310 [inline]
 kfree+0x1c5/0x640 mm/slub.c:6625
 __kthread_create_on_node+0x2fe/0x3d0 kernel/kthread.c:523
 kthread_create_on_node+0xeb/0x140 kernel/kthread.c:559
 napi_kthread_create net/core/dev.c:1656 [inline]
 netif_napi_add_weight_locked+0x699/0x940 net/core/dev.c:7594
 netif_napi_add_weight include/linux/netdevice.h:2870 [inline]
 netif_napi_add include/linux/netdevice.h:2887 [inline]
 wg_peer_create+0x52d/0x860 drivers/net/wireguard/peer.c:57
 set_peer drivers/net/wireguard/netlink.c:392 [inline]
 wg_set_device_doit+0xf3a/0x2120 drivers/net/wireguard/netlink.c:569
 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
 __sock_sendmsg net/socket.c:790 [inline]
 __sys_sendto+0x408/0x5a0 net/socket.c:2252
 __do_sys_sendto net/socket.c:2259 [inline]
 __se_sys_sendto net/socket.c:2255 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2255
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888111d01480
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 29 bytes inside of
 freed 64-byte region [ffff888111d01480, ffff888111d014c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x111d01
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1113, tgid 1113 (kworker/u9:4), ts 18841797934, free_ts 18841792693
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x24ae/0x2530 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3289 [inline]
 allocate_slab+0x74/0x5d0 mm/slub.c:3404
 new_slab mm/slub.c:3447 [inline]
 refill_objects+0x328/0x3c0 mm/slub.c:7241
 refill_sheaf mm/slub.c:2827 [inline]
 __pcs_replace_empty_main+0x2e0/0x6b0 mm/slub.c:4692
 alloc_from_pcs mm/slub.c:4790 [inline]
 slab_alloc_node mm/slub.c:4924 [inline]
 __do_kmalloc_node mm/slub.c:5333 [inline]
 __kmalloc_node_noprof+0x56a/0x7b0 mm/slub.c:5340
 _kmalloc_node_noprof include/linux/slab.h:1174 [inline]
 __vmalloc_area_node mm/vmalloc.c:3857 [inline]
 __vmalloc_node_range_noprof+0x5d9/0x1730 mm/vmalloc.c:4064
 __vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4124
 alloc_thread_stack_node kernel/fork.c:358 [inline]
 dup_task_struct+0x28e/0x850 kernel/fork.c:928
 copy_process+0x81b/0x42e0 kernel/fork.c:2109
 kernel_clone+0x2d7/0x940 kernel/fork.c:2745
 user_mode_thread+0x110/0x180 kernel/fork.c:2821
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
page last free pid 1113 tgid 1113 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1397 [inline]
 __free_frozen_pages+0xc0d/0xd20 mm/page_alloc.c:2938
 __kasan_populate_vmalloc_do mm/kasan/shadow.c:393 [inline]
 __kasan_populate_vmalloc+0x1a8/0x1c0 mm/kasan/shadow.c:424
 kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
 alloc_vmap_area+0xd1a/0x1420 mm/vmalloc.c:2123
 __get_vm_area_node+0x1f2/0x300 mm/vmalloc.c:3226
 __vmalloc_node_range_noprof+0x358/0x1730 mm/vmalloc.c:4024
 __vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4124
 alloc_thread_stack_node kernel/fork.c:358 [inline]
 dup_task_struct+0x28e/0x850 kernel/fork.c:928
 copy_process+0x81b/0x42e0 kernel/fork.c:2109
 kernel_clone+0x2d7/0x940 kernel/fork.c:2745
 user_mode_thread+0x110/0x180 kernel/fork.c:2821
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888111d01380: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
 ffff888111d01400: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888111d01480: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                            ^
 ffff888111d01500: 00 00 00 00 00 00 02 fc fc fc fc fc fc fc fc fc
 ffff888111d01580: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: use-after-free Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      08c7183f5b9ffe4408e74fff848a4cc2105361d4
arch:      amd64
compiler:  Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
config:    https://ci.syzbot.org/builds/0efdb868-daeb-4649-9bcb-5af41d993e73/config
syz repro: https://ci.syzbot.org/findings/07c4f835-36f6-4535-a165-aa25c5af571c/syz_repro

EXT4-fs error (device loop2): ext4_inlinedir_to_tree:1343: inode #21: block 10: comm syz.2.19: path /: bad entry in directory: directory entry overrun - offset=20, inode=0, rec_len=1024, size=60 fake=0
==================================================================
BUG: KASAN: use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4156 [inline]
BUG: KASAN: use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4183 [inline]
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x659/0xbe0 fs/ext4/dir.c:96
Read of size 1 at addr ffff888112785045 by task syz.2.19/5869

CPU: 0 UID: 0 PID: 5869 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4156 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4183 [inline]
 __ext4_check_dir_entry+0x659/0xbe0 fs/ext4/dir.c:96
 ext4_find_dest_de+0x14e/0x6e0 fs/ext4/namei.c:2221
 ext4_add_dirent_to_inline+0xcc/0x410 fs/ext4/inline.c:984
 ext4_try_add_inline_entry+0x21e/0x8a0 fs/ext4/inline.c:1213
 __ext4_add_entry+0x385/0x3470 fs/ext4/namei.c:2552
 __ext4_link+0x498/0x720 fs/ext4/namei.c:3649
 ext4_link+0x1dc/0x2b0 fs/ext4/namei.c:3689
 vfs_link+0x491/0x650 fs/namei.c:5787
 ovl_do_link fs/overlayfs/overlayfs.h:233 [inline]
 ovl_copy_up_tmpfile fs/overlayfs/copy_up.c:891 [inline]
 ovl_do_copy_up fs/overlayfs/copy_up.c:986 [inline]
 ovl_copy_up_one fs/overlayfs/copy_up.c:1189 [inline]
 ovl_copy_up_flags+0x1c52/0x3930 fs/overlayfs/copy_up.c:1243
 ovl_open+0x13f/0x300 fs/overlayfs/file.c:211
 do_dentry_open+0x816/0x1380 fs/open.c:947
 vfs_open+0x3b/0x340 fs/open.c:1079
 dentry_open+0x61/0xa0 fs/open.c:1102
 ima_calc_file_hash+0x15f/0x890 security/integrity/ima/ima_crypto.c:269
 ima_collect_measurement+0x51b/0xa00 security/integrity/ima/ima_api.c:300
 process_measurement+0x1272/0x1c10 security/integrity/ima/ima_main.c:425
 ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
 security_file_post_open+0xb3/0x260 security/security.c:2755
 do_open fs/namei.c:4702 [inline]
 path_openat+0x2e90/0x3830 fs/namei.c:4859
 do_file_open+0x23e/0x4a0 fs/namei.c:4888
 do_sys_openat2+0x115/0x200 fs/open.c:1395
 do_sys_open fs/open.c:1401 [inline]
 __do_sys_openat fs/open.c:1417 [inline]
 __se_sys_openat fs/open.c:1412 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1412
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fae54f9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fae55ddb028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fae55215fa0 RCX: 00007fae54f9ce59
RDX: 000000000000003f RSI: 0000200000000380 RDI: ffffffffffffff9c
RBP: 00007fae55032e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000186 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fae55216038 R14: 00007fae55215fa0 R15: 00007ffedd6a9a88
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x112785
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 017ff00000000000 ffffea000449e048 ffffea000449e2c8 0000000000000000
raw: 0000000000000000 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xcc0(GFP_KERNEL), pid 26, tgid 26 (kworker/u9:0), ts 18747225753, free_ts 49527089310
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x24ae/0x2530 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 __alloc_pages_noprof+0x10/0x100 mm/page_alloc.c:5255
 alloc_pages_bulk_noprof+0x5ff/0x7c0 mm/page_alloc.c:5175
 ___alloc_pages_bulk mm/kasan/shadow.c:345 [inline]
 __kasan_populate_vmalloc_do mm/kasan/shadow.c:370 [inline]
 __kasan_populate_vmalloc+0xb7/0x1c0 mm/kasan/shadow.c:424
 kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
 alloc_vmap_area+0xd1a/0x1420 mm/vmalloc.c:2123
 __get_vm_area_node+0x1f2/0x300 mm/vmalloc.c:3226
 __vmalloc_node_range_noprof+0x358/0x1730 mm/vmalloc.c:4024
 __vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4124
 alloc_thread_stack_node kernel/fork.c:358 [inline]
 dup_task_struct+0x28e/0x850 kernel/fork.c:928
 copy_process+0x81b/0x42e0 kernel/fork.c:2109
 kernel_clone+0x2d7/0x940 kernel/fork.c:2745
 user_mode_thread+0x110/0x180 kernel/fork.c:2821
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
page last free pid 5625 tgid 5625 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1397 [inline]
 __free_frozen_pages+0xc0d/0xd20 mm/page_alloc.c:2938
 kasan_depopulate_vmalloc_pte+0x6d/0x90 mm/kasan/shadow.c:484
 apply_to_pte_range mm/memory.c:3338 [inline]
 apply_to_pmd_range mm/memory.c:3382 [inline]
 apply_to_pud_range mm/memory.c:3418 [inline]
 apply_to_p4d_range mm/memory.c:3454 [inline]
 __apply_to_page_range+0xbd8/0x1420 mm/memory.c:3490
 __kasan_release_vmalloc+0xa2/0xd0 mm/kasan/shadow.c:602
 kasan_release_vmalloc include/linux/kasan.h:593 [inline]
 kasan_release_vmalloc_node mm/vmalloc.c:2284 [inline]
 purge_vmap_node+0x220/0x960 mm/vmalloc.c:2306
 __purge_vmap_area_lazy+0x783/0xb40 mm/vmalloc.c:2396
 drain_vmap_area_work+0x27/0x40 mm/vmalloc.c:2430
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888112784f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888112784f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888112785000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff888112785080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888112785100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@syzkaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.

To test a patch for this bug, please reply with `#syz test`
(should be on a separate line).

The patch should be attached to the email.
Note: arguments like custom git repos and branches are not supported.

[PATCH 0/3] Data in direntry (dirdata) feature

[Artem Blagodarenko]

EXT4 currently stores a hash in the directory entry
(dirent) immediately after the file name to support
simultaneous fscrypt and casefold functionality.

It has been discussed within the EXT4 community that
this hash could instead be stored in dirdata. This
would make it the second (or third, in the case of
64-bit inode counts) user of dirdata.

At the same time, the existing format—where the hash
is placed after the file name—must continue to be
supported. With these patches, EXT4 can handle the
hash in both formats.

The first user of this feature, LUFID, has been
tested in the Lustre filesystem backend (LDISKFS)
[1].

Support for fscrypt and case-insensitive directories
with dirdata enabled has been verified using a
dedicated xfstest submitted to the EXT4 community as
a separate patch.

e2fsprogs support is provided in a separate patch.

[1] https://review.whamcloud.com/c/fs/lustre-release/+/64439

Artem Blagodarenko (3):
  ext4: make dirdata work with metadata_csum
  ext4: add dirdata support structures and helpers
  ext4: dirdata feature

 fs/ext4/dir.c    |   9 +-
 fs/ext4/ext4.h   | 169 +++++++++++++++++++--
 fs/ext4/inline.c |  22 +--
 fs/ext4/namei.c  | 379 ++++++++++++++++++++++++++++++-----------------
 fs/ext4/super.c  |   4 +-
 fs/ext4/sysfs.c  |   2 +
 6 files changed, 422 insertions(+), 163 deletions(-)

-- 
2.43.5

[syzbot ci] Re: Data in direntry (dirdata) feature

[syzbot ci]

syzbot ci has tested the following series

[v1] Data in direntry (dirdata) feature
https://lore.kernel.org/all/20260417213723.74204-1-artem.blagodarenko@gmail.com
* [PATCH 1/3] ext4: make dirdata work with metadata_csum
* [PATCH 2/3] ext4: add dirdata support structures and helpers
* [PATCH 3/3] ext4: dirdata feature

and found the following issues:
* KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
* KASAN: slab-out-of-bounds Read in dx_probe
* KASAN: slab-use-after-free Read in __ext4_check_dir_entry
* KASAN: slab-use-after-free Read in dx_probe
* KASAN: use-after-free Read in __ext4_check_dir_entry

Full report is available here:
https://ci.syzbot.org/series/590e846e-42c0-4497-b6ae-b95ed4468941

***

KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      70b672833f4025341c11b22c7f83778a5cd611bc
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/7b860156-1ca9-441f-b899-ebfb5a09620d/config
syz repro: https://ci.syzbot.org/findings/d27eccd2-4663-4047-abb9-9c24cb32f887/syz_repro

loop0: lost filesystem error report for type 5 error -117
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
Read of size 1 at addr ffff8881090bfe5c by task syz.0.20/5967

CPU: 1 UID: 0 PID: 5967 Comm: syz.0.20 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
 __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
 ext4_inlinedir_to_tree+0x6be/0xbf0 fs/ext4/inline.c:1322
 ext4_htree_fill_tree+0x50b/0x1230 fs/ext4/namei.c:1184
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2f7b/0x3870 fs/ext4/dir.c:146
 iterate_dir+0x399/0x570 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:412 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:397
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe47219c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe4730c0028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fe472415fa0 RCX: 00007fe47219c819
RDX: 000000000000ff80 RSI: 9999999999999999 RDI: 0000000000000004
RBP: 00007fe472232c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe472416038 R14: 00007fe472415fa0 R15: 00007ffff595c618
 </TASK>

Allocated by task 5967:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5260 [inline]
 __kmalloc_noprof+0x35c/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 ext4_mb_init+0x15d/0x2ad0 fs/ext4/mballoc.c:3729
 __ext4_fill_super fs/ext4/super.c:5623 [inline]
 ext4_fill_super+0x5647/0x6320 fs/ext4/super.c:5793
 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3839
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8881090bfe00
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 44 bytes to the right of
 allocated 48-byte region [ffff8881090bfe00, ffff8881090bfe30)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1090bf
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 16414655371, free_ts 15537272896
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 kobject_get_path+0xc5/0x2f0 lib/kobject.c:161
 kobject_uevent_env+0x2a1/0x9e0 lib/kobject_uevent.c:545
 really_probe+0x789/0xaf0 drivers/base/dd.c:771
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:863
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:893
 __device_attach_driver+0x279/0x430 drivers/base/dd.c:1021
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2c5/0x450 drivers/base/dd.c:1093
 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1148
page last free pid 33 tgid 33 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 vfree+0x25a/0x400 mm/vmalloc.c:3479
 delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3398
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff8881090bfd00: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
 ffff8881090bfd80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff8881090bfe00: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
                                                    ^
 ffff8881090bfe80: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8881090bff00: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: slab-out-of-bounds Read in dx_probe

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      70b672833f4025341c11b22c7f83778a5cd611bc
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/7b860156-1ca9-441f-b899-ebfb5a09620d/config
syz repro: https://ci.syzbot.org/findings/a5fcf3bd-f1ae-4b81-b5d2-f96899ea7690/syz_repro

==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_is_tail fs/ext4/ext4.h:4001 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_dirent_get_data_len fs/ext4/ext4.h:4024 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
BUG: KASAN: slab-out-of-bounds in dx_root_limit fs/ext4/namei.c:583 [inline]
BUG: KASAN: slab-out-of-bounds in dx_probe+0x1ac9/0x1d90 fs/ext4/namei.c:861
Read of size 4 at addr ffff88816a408c10 by task syz.2.19/5980

CPU: 1 UID: 0 PID: 5980 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dir_entry_is_tail fs/ext4/ext4.h:4001 [inline]
 ext4_dirent_get_data_len fs/ext4/ext4.h:4024 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
 dx_root_limit fs/ext4/namei.c:583 [inline]
 dx_probe+0x1ac9/0x1d90 fs/ext4/namei.c:861
 ext4_dx_find_entry fs/ext4/namei.c:1812 [inline]
 __ext4_find_entry+0x5a9/0x2140 fs/ext4/namei.c:1652
 ext4_lookup_entry fs/ext4/namei.c:1794 [inline]
 ext4_lookup+0x17b/0x710 fs/ext4/namei.c:1860
 __lookup_slow+0x2b7/0x410 fs/namei.c:1916
 lookup_slow+0x53/0x70 fs/namei.c:1933
 walk_component fs/namei.c:2279 [inline]
 lookup_last fs/namei.c:2780 [inline]
 path_lookupat+0x3f5/0x8c0 fs/namei.c:2804
 filename_lookup+0x256/0x5d0 fs/namei.c:2833
 user_path_at+0x40/0x160 fs/namei.c:3612
 do_mount fs/namespace.c:4169 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x2dc/0x420 fs/namespace.c:4338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f518919c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5189fbb028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f5189415fa0 RCX: 00007f518919c819
RDX: 0000200000000140 RSI: 0000200000000100 RDI: 0000000000000000
RBP: 00007f5189232c91 R08: 0000200000000d80 R09: 0000000000000000
R10: 0000000001302060 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5189416038 R14: 00007f5189415fa0 R15: 00007ffc5d8d15b8
 </TASK>

Allocated by task 5243:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5260 [inline]
 __kvmalloc_node_noprof+0x528/0x8a0 mm/slub.c:6752
 evdev_open+0xeb/0x5b0 drivers/input/evdev.c:468
 chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411
 do_dentry_open+0x785/0x14e0 fs/open.c:949
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88816a408000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1088 bytes to the right of
 allocated 2000-byte region [ffff88816a408000, ffff88816a4087d0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16a408
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff888100042000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff888100042000 dead000000000100 dead000000000122
head: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 057ff00000000003 ffffea0005a90201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5243, tgid 5243 (acpid), ts 25906150911, free_ts 21905842969
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kvmalloc_node_noprof+0x657/0x8a0 mm/slub.c:6752
 evdev_open+0xeb/0x5b0 drivers/input/evdev.c:468
 chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411
 do_dentry_open+0x785/0x14e0 fs/open.c:949
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
page last free pid 9 tgid 9 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 vfree+0x25a/0x400 mm/vmalloc.c:3479
 delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3398
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff88816a408b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88816a408b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88816a408c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff88816a408c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88816a408d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: slab-use-after-free Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      70b672833f4025341c11b22c7f83778a5cd611bc
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/7b860156-1ca9-441f-b899-ebfb5a09620d/config
syz repro: https://ci.syzbot.org/findings/e493ff66-4032-4979-9b5d-5118b2768ca5/syz_repro

EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
BUG: KASAN: slab-use-after-free in __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
Read of size 1 at addr ffff88810138889c by task syz.0.24/5978

CPU: 0 UID: 0 PID: 5978 Comm: syz.0.24 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
 __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
 ext4_inlinedir_to_tree+0x6be/0xbf0 fs/ext4/inline.c:1322
 ext4_htree_fill_tree+0x50b/0x1230 fs/ext4/namei.c:1184
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2f7b/0x3870 fs/ext4/dir.c:146
 iterate_dir+0x399/0x570 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:412 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:397
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff3fe19c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff3fefac028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007ff3fe415fa0 RCX: 00007ff3fe19c819
RDX: 000000000000ff80 RSI: 9999999999999999 RDI: 0000000000000004
RBP: 00007ff3fe232c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff3fe416038 R14: 00007ff3fe415fa0 R15: 00007ffd39a74998
 </TASK>

Allocated by task 5766:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5260 [inline]
 __kmalloc_noprof+0x35c/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
 tomoyo_encode+0x28b/0x550 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x58d/0x5d0 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_check_open_permission+0x229/0x470 security/tomoyo/file.c:776
 security_file_open+0xa9/0x240 security/security.c:2637
 do_dentry_open+0x384/0x14e0 fs/open.c:926
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5766:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2685 [inline]
 slab_free mm/slub.c:6165 [inline]
 kfree+0x1c1/0x630 mm/slub.c:6483
 tomoyo_check_open_permission+0x32c/0x470 security/tomoyo/file.c:791
 security_file_open+0xa9/0x240 security/security.c:2637
 do_dentry_open+0x384/0x14e0 fs/open.c:926
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888101388880
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 28 bytes inside of
 freed 64-byte region [ffff888101388880, ffff8881013888c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x101388
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 26, tgid 26 (kworker/u9:0), ts 4100832473, free_ts 4100767003
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 alloc_full_sheaf mm/slub.c:2834 [inline]
 __pcs_replace_empty_main+0x40a/0x730 mm/slub.c:4626
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 lsm_blob_alloc security/security.c:193 [inline]
 lsm_task_alloc security/security.c:245 [inline]
 security_task_alloc+0x4d/0x330 security/security.c:2683
 copy_process+0x16df/0x3cd0 kernel/fork.c:2206
 kernel_clone+0x248/0x8e0 kernel/fork.c:2658
 user_mode_thread+0x110/0x180 kernel/fork.c:2734
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
page last free pid 26 tgid 26 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 __kasan_populate_vmalloc_do mm/kasan/shadow.c:393 [inline]
 __kasan_populate_vmalloc+0x1b2/0x1d0 mm/kasan/shadow.c:424
 kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
 alloc_vmap_area+0xd73/0x14b0 mm/vmalloc.c:2129
 __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3232
 __vmalloc_node_range_noprof+0x372/0x1730 mm/vmalloc.c:4024
 __vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4124
 alloc_thread_stack_node kernel/fork.c:355 [inline]
 dup_task_struct+0x292/0x9e0 kernel/fork.c:924
 copy_process+0x508/0x3cd0 kernel/fork.c:2051
 kernel_clone+0x248/0x8e0 kernel/fork.c:2658
 user_mode_thread+0x110/0x180 kernel/fork.c:2734
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888101388780: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
 ffff888101388800: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888101388880: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                            ^
 ffff888101388900: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
 ffff888101388980: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: slab-use-after-free Read in dx_probe

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      70b672833f4025341c11b22c7f83778a5cd611bc
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/7b860156-1ca9-441f-b899-ebfb5a09620d/config
syz repro: https://ci.syzbot.org/findings/5524eff5-62fb-4cff-8d4e-7e3750aa921b/syz_repro

EXT4-fs (loop2): mounted filesystem 00000000-0000-0000-0000-000000000000 ro without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-use-after-free in ext4_dir_entry_is_tail fs/ext4/ext4.h:4001 [inline]
BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4024 [inline]
BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
BUG: KASAN: slab-use-after-free in dx_root_limit fs/ext4/namei.c:583 [inline]
BUG: KASAN: slab-use-after-free in dx_probe+0x1ac9/0x1d90 fs/ext4/namei.c:861
Read of size 4 at addr ffff888109c42c10 by task syz.2.20/5984

CPU: 0 UID: 0 PID: 5984 Comm: syz.2.20 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dir_entry_is_tail fs/ext4/ext4.h:4001 [inline]
 ext4_dirent_get_data_len fs/ext4/ext4.h:4024 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
 dx_root_limit fs/ext4/namei.c:583 [inline]
 dx_probe+0x1ac9/0x1d90 fs/ext4/namei.c:861
 ext4_dx_find_entry fs/ext4/namei.c:1812 [inline]
 __ext4_find_entry+0x5a9/0x2140 fs/ext4/namei.c:1652
 ext4_lookup_entry fs/ext4/namei.c:1794 [inline]
 ext4_lookup+0x17b/0x710 fs/ext4/namei.c:1860
 lookup_open fs/namei.c:4456 [inline]
 open_last_lookups fs/namei.c:4583 [inline]
 path_openat+0x11ac/0x3860 fs/namei.c:4827
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb97dd9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb97ec96028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fb97e015fa0 RCX: 00007fb97dd9c819
RDX: 0000000000042041 RSI: 0000200000000700 RDI: ffffffffffffff9c
RBP: 00007fb97de32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000001d R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb97e016038 R14: 00007fb97e015fa0 R15: 00007fffcac5f5a8
 </TASK>

Allocated by task 5828:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5260 [inline]
 __kmalloc_noprof+0x35c/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
 tomoyo_path_symlink+0xab/0xf0 security/tomoyo/tomoyo.c:212
 security_path_symlink+0x16f/0x360 security/security.c:1477
 filename_symlinkat+0x134/0x410 fs/namei.c:5638
 __do_sys_symlink fs/namei.c:5667 [inline]
 __se_sys_symlink+0x4d/0x2b0 fs/namei.c:5663
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5828:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2685 [inline]
 slab_free mm/slub.c:6165 [inline]
 kfree+0x1c1/0x630 mm/slub.c:6483
 tomoyo_realpath_from_path+0x598/0x5d0 security/tomoyo/realpath.c:286
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
 tomoyo_path_symlink+0xab/0xf0 security/tomoyo/tomoyo.c:212
 security_path_symlink+0x16f/0x360 security/security.c:1477
 filename_symlinkat+0x134/0x410 fs/namei.c:5638
 __do_sys_symlink fs/namei.c:5667 [inline]
 __se_sys_symlink+0x4d/0x2b0 fs/namei.c:5663
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888109c42000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 3088 bytes inside of
 freed 4096-byte region [ffff888109c42000, ffff888109c43000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x109c40
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000040 ffff888100042140 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
head: 017ff00000000040 ffff888100042140 dead000000000100 dead000000000122
head: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
head: 017ff00000000003 ffffea0004271001 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5828, tgid 5828 (udevd), ts 67573015608, free_ts 47549723112
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
 tomoyo_path_symlink+0xab/0xf0 security/tomoyo/tomoyo.c:212
 security_path_symlink+0x16f/0x360 security/security.c:1477
 filename_symlinkat+0x134/0x410 fs/namei.c:5638
 __do_sys_symlink fs/namei.c:5667 [inline]
 __se_sys_symlink+0x4d/0x2b0 fs/namei.c:5663
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5718 tgid 5718 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 __slab_free+0x263/0x2b0 mm/slub.c:5573
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4538 [inline]
 slab_alloc_node mm/slub.c:4866 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4873
 alloc_filename fs/namei.c:142 [inline]
 do_getname+0x2e/0x250 fs/namei.c:182
 getname include/linux/fs.h:2512 [inline]
 getname_maybe_null include/linux/fs.h:2519 [inline]
 class_filename_maybe_null_constructor include/linux/fs.h:2543 [inline]
 vfs_fstatat+0x45/0x170 fs/stat.c:368
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat fs/stat.c:532 [inline]
 __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888109c42b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888109c42b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888109c42c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888109c42c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888109c42d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


***

KASAN: use-after-free Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      70b672833f4025341c11b22c7f83778a5cd611bc
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/7b860156-1ca9-441f-b899-ebfb5a09620d/config
syz repro: https://ci.syzbot.org/findings/21333690-a422-407b-92c7-9247a0075b74/syz_repro

loop1: lost filesystem error report for type 5 error -117
EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
BUG: KASAN: use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
Read of size 1 at addr ffff88810da3609c by task syz.1.20/5966

CPU: 0 UID: 0 PID: 5966 Comm: syz.1.20 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
 __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
 ext4_inlinedir_to_tree+0x6be/0xbf0 fs/ext4/inline.c:1322
 ext4_htree_fill_tree+0x50b/0x1230 fs/ext4/namei.c:1184
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2f7b/0x3870 fs/ext4/dir.c:146
 iterate_dir+0x399/0x570 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:412 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:397
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb82a19c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb82b01a028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fb82a415fa0 RCX: 00007fb82a19c819
RDX: 000000000000ff80 RSI: 9999999999999999 RDI: 0000000000000004
RBP: 00007fb82a232c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb82a416038 R14: 00007fb82a415fa0 R15: 00007ffdc30464e8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88810da36000 pfn:0x10da36
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 017ff00000000000 ffffea0004364708 ffffea000436a7c8 0000000000000000
raw: ffff88810da36000 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2c00(GFP_NOIO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 15037633903, free_ts 26770192426
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 usb_alloc_urb+0x46/0x150 drivers/usb/core/urb.c:75
 usb_internal_control_msg drivers/usb/core/message.c:110 [inline]
 usb_control_msg+0x118/0x3e0 drivers/usb/core/message.c:167
 usb_get_descriptor+0xb1/0x3e0 drivers/usb/core/message.c:852
 usb_get_configuration+0x3b9/0x54f0 drivers/usb/core/config.c:986
 usb_enumerate_device drivers/usb/core/hub.c:2527 [inline]
 usb_new_device+0x145/0x16f0 drivers/usb/core/hub.c:2665
 register_root_hub+0x270/0x5f0 drivers/usb/core/hcd.c:990
 usb_add_hcd+0xba1/0x10b0 drivers/usb/core/hcd.c:2987
 vhci_hcd_probe+0x1fa/0x3e0 drivers/usb/usbip/vhci_hcd.c:1401
 platform_probe+0xf9/0x190 drivers/base/platform.c:1418
page last free pid 5262 tgid 5262 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 __slab_free+0x263/0x2b0 mm/slub.c:5573
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4538 [inline]
 slab_alloc_node mm/slub.c:4866 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4873
 alloc_empty_file+0x55/0x1d0 fs/file_table.c:237
 path_openat+0x10f/0x3860 fs/namei.c:4816
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88810da35f80: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
 ffff88810da36000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88810da36080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88810da36100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88810da36180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@syzkaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.

To test a patch for this bug, please reply with `#syz test`
(should be on a separate line).

The patch should be attached to the email.
Note: arguments like custom git repos and branches are not supported.

Re: [syzbot ci] Re: Data in direntry (dirdata) feature

[Artem Blagodarenko]

[-- Attachment #1.1: Type: text/plain, Size: 42587 bytes --]

#syz test


From: syzbot ci <syzbot+ci6167b51351f50705@syzkaller.appspotmail.com>
Date: Saturday, 18 April 2026 at 07:47
To: adilger.kernel@dilger.ca <adilger.kernel@dilger.ca>, adilger@dilger.ca <adilger@dilger.ca>, artem.blagodarenko@gmail.com <artem.blagodarenko@gmail.com>, linux-ext4@vger.kernel.org <linux-ext4@vger.kernel.org>, pravin.shelar@sun.com <pravin.shelar@sun.com>
Cc: syzbot@lists.linux.dev <syzbot@lists.linux.dev>, syzkaller-bugs@googlegroups.com <syzkaller-bugs@googlegroups.com>
Subject: [syzbot ci] Re: Data in direntry (dirdata) feature

syzbot ci has tested the following series

[v1] Data in direntry (dirdata) feature
https://lore.kernel.org/all/20260417213723.74204-1-artem.blagodarenko@gmail.com
* [PATCH 1/3] ext4: make dirdata work with metadata_csum
* [PATCH 2/3] ext4: add dirdata support structures and helpers
* [PATCH 3/3] ext4: dirdata feature

and found the following issues:
* KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry
* KASAN: slab-out-of-bounds Read in dx_probe
* KASAN: slab-use-after-free Read in __ext4_check_dir_entry
* KASAN: slab-use-after-free Read in dx_probe
* KASAN: use-after-free Read in __ext4_check_dir_entry

Full report is available here:
https://ci.syzbot.org/series/590e846e-42c0-4497-b6ae-b95ed4468941

***

KASAN: slab-out-of-bounds Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      70b672833f4025341c11b22c7f83778a5cd611bc
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/7b860156-1ca9-441f-b899-ebfb5a09620d/config
syz repro: https://ci.syzbot.org/findings/d27eccd2-4663-4047-abb9-9c24cb32f887/syz_repro

loop0: lost filesystem error report for type 5 error -117
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
Read of size 1 at addr ffff8881090bfe5c by task syz.0.20/5967

CPU: 1 UID: 0 PID: 5967 Comm: syz.0.20 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
 __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
 ext4_inlinedir_to_tree+0x6be/0xbf0 fs/ext4/inline.c:1322
 ext4_htree_fill_tree+0x50b/0x1230 fs/ext4/namei.c:1184
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2f7b/0x3870 fs/ext4/dir.c:146
 iterate_dir+0x399/0x570 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:412 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:397
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe47219c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe4730c0028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fe472415fa0 RCX: 00007fe47219c819
RDX: 000000000000ff80 RSI: 9999999999999999 RDI: 0000000000000004
RBP: 00007fe472232c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe472416038 R14: 00007fe472415fa0 R15: 00007ffff595c618
 </TASK>

Allocated by task 5967:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5260 [inline]
 __kmalloc_noprof+0x35c/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 ext4_mb_init+0x15d/0x2ad0 fs/ext4/mballoc.c:3729
 __ext4_fill_super fs/ext4/super.c:5623 [inline]
 ext4_fill_super+0x5647/0x6320 fs/ext4/super.c:5793
 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3839
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8881090bfe00
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 44 bytes to the right of
 allocated 48-byte region [ffff8881090bfe00, ffff8881090bfe30)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1090bf
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 16414655371, free_ts 15537272896
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 kobject_get_path+0xc5/0x2f0 lib/kobject.c:161
 kobject_uevent_env+0x2a1/0x9e0 lib/kobject_uevent.c:545
 really_probe+0x789/0xaf0 drivers/base/dd.c:771
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:863
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:893
 __device_attach_driver+0x279/0x430 drivers/base/dd.c:1021
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2c5/0x450 drivers/base/dd.c:1093
 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1148
page last free pid 33 tgid 33 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 vfree+0x25a/0x400 mm/vmalloc.c:3479
 delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3398
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff8881090bfd00: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
 ffff8881090bfd80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff8881090bfe00: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
                                                    ^
 ffff8881090bfe80: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8881090bff00: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: slab-out-of-bounds Read in dx_probe

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      70b672833f4025341c11b22c7f83778a5cd611bc
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/7b860156-1ca9-441f-b899-ebfb5a09620d/config
syz repro: https://ci.syzbot.org/findings/a5fcf3bd-f1ae-4b81-b5d2-f96899ea7690/syz_repro

==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_is_tail fs/ext4/ext4.h:4001 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_dirent_get_data_len fs/ext4/ext4.h:4024 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
BUG: KASAN: slab-out-of-bounds in dx_root_limit fs/ext4/namei.c:583 [inline]
BUG: KASAN: slab-out-of-bounds in dx_probe+0x1ac9/0x1d90 fs/ext4/namei.c:861
Read of size 4 at addr ffff88816a408c10 by task syz.2.19/5980

CPU: 1 UID: 0 PID: 5980 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dir_entry_is_tail fs/ext4/ext4.h:4001 [inline]
 ext4_dirent_get_data_len fs/ext4/ext4.h:4024 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
 dx_root_limit fs/ext4/namei.c:583 [inline]
 dx_probe+0x1ac9/0x1d90 fs/ext4/namei.c:861
 ext4_dx_find_entry fs/ext4/namei.c:1812 [inline]
 __ext4_find_entry+0x5a9/0x2140 fs/ext4/namei.c:1652
 ext4_lookup_entry fs/ext4/namei.c:1794 [inline]
 ext4_lookup+0x17b/0x710 fs/ext4/namei.c:1860
 __lookup_slow+0x2b7/0x410 fs/namei.c:1916
 lookup_slow+0x53/0x70 fs/namei.c:1933
 walk_component fs/namei.c:2279 [inline]
 lookup_last fs/namei.c:2780 [inline]
 path_lookupat+0x3f5/0x8c0 fs/namei.c:2804
 filename_lookup+0x256/0x5d0 fs/namei.c:2833
 user_path_at+0x40/0x160 fs/namei.c:3612
 do_mount fs/namespace.c:4169 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x2dc/0x420 fs/namespace.c:4338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f518919c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5189fbb028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f5189415fa0 RCX: 00007f518919c819
RDX: 0000200000000140 RSI: 0000200000000100 RDI: 0000000000000000
RBP: 00007f5189232c91 R08: 0000200000000d80 R09: 0000000000000000
R10: 0000000001302060 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5189416038 R14: 00007f5189415fa0 R15: 00007ffc5d8d15b8
 </TASK>

Allocated by task 5243:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5260 [inline]
 __kvmalloc_node_noprof+0x528/0x8a0 mm/slub.c:6752
 evdev_open+0xeb/0x5b0 drivers/input/evdev.c:468
 chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411
 do_dentry_open+0x785/0x14e0 fs/open.c:949
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88816a408000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1088 bytes to the right of
 allocated 2000-byte region [ffff88816a408000, ffff88816a4087d0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16a408
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff888100042000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff888100042000 dead000000000100 dead000000000122
head: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 057ff00000000003 ffffea0005a90201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5243, tgid 5243 (acpid), ts 25906150911, free_ts 21905842969
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kvmalloc_node_noprof+0x657/0x8a0 mm/slub.c:6752
 evdev_open+0xeb/0x5b0 drivers/input/evdev.c:468
 chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411
 do_dentry_open+0x785/0x14e0 fs/open.c:949
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
page last free pid 9 tgid 9 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 vfree+0x25a/0x400 mm/vmalloc.c:3479
 delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3398
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff88816a408b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88816a408b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88816a408c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff88816a408c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88816a408d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: slab-use-after-free Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      70b672833f4025341c11b22c7f83778a5cd611bc
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/7b860156-1ca9-441f-b899-ebfb5a09620d/config
syz repro: https://ci.syzbot.org/findings/e493ff66-4032-4979-9b5d-5118b2768ca5/syz_repro

EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
BUG: KASAN: slab-use-after-free in __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
Read of size 1 at addr ffff88810138889c by task syz.0.24/5978

CPU: 0 UID: 0 PID: 5978 Comm: syz.0.24 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
 __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
 ext4_inlinedir_to_tree+0x6be/0xbf0 fs/ext4/inline.c:1322
 ext4_htree_fill_tree+0x50b/0x1230 fs/ext4/namei.c:1184
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2f7b/0x3870 fs/ext4/dir.c:146
 iterate_dir+0x399/0x570 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:412 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:397
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff3fe19c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff3fefac028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007ff3fe415fa0 RCX: 00007ff3fe19c819
RDX: 000000000000ff80 RSI: 9999999999999999 RDI: 0000000000000004
RBP: 00007ff3fe232c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff3fe416038 R14: 00007ff3fe415fa0 R15: 00007ffd39a74998
 </TASK>

Allocated by task 5766:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5260 [inline]
 __kmalloc_noprof+0x35c/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
 tomoyo_encode+0x28b/0x550 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x58d/0x5d0 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_check_open_permission+0x229/0x470 security/tomoyo/file.c:776
 security_file_open+0xa9/0x240 security/security.c:2637
 do_dentry_open+0x384/0x14e0 fs/open.c:926
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5766:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2685 [inline]
 slab_free mm/slub.c:6165 [inline]
 kfree+0x1c1/0x630 mm/slub.c:6483
 tomoyo_check_open_permission+0x32c/0x470 security/tomoyo/file.c:791
 security_file_open+0xa9/0x240 security/security.c:2637
 do_dentry_open+0x384/0x14e0 fs/open.c:926
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888101388880
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 28 bytes inside of
 freed 64-byte region [ffff888101388880, ffff8881013888c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x101388
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000000 ffff8881000418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 26, tgid 26 (kworker/u9:0), ts 4100832473, free_ts 4100767003
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 alloc_full_sheaf mm/slub.c:2834 [inline]
 __pcs_replace_empty_main+0x40a/0x730 mm/slub.c:4626
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 lsm_blob_alloc security/security.c:193 [inline]
 lsm_task_alloc security/security.c:245 [inline]
 security_task_alloc+0x4d/0x330 security/security.c:2683
 copy_process+0x16df/0x3cd0 kernel/fork.c:2206
 kernel_clone+0x248/0x8e0 kernel/fork.c:2658
 user_mode_thread+0x110/0x180 kernel/fork.c:2734
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
page last free pid 26 tgid 26 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 __kasan_populate_vmalloc_do mm/kasan/shadow.c:393 [inline]
 __kasan_populate_vmalloc+0x1b2/0x1d0 mm/kasan/shadow.c:424
 kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
 alloc_vmap_area+0xd73/0x14b0 mm/vmalloc.c:2129
 __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3232
 __vmalloc_node_range_noprof+0x372/0x1730 mm/vmalloc.c:4024
 __vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4124
 alloc_thread_stack_node kernel/fork.c:355 [inline]
 dup_task_struct+0x292/0x9e0 kernel/fork.c:924
 copy_process+0x508/0x3cd0 kernel/fork.c:2051
 kernel_clone+0x248/0x8e0 kernel/fork.c:2658
 user_mode_thread+0x110/0x180 kernel/fork.c:2734
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888101388780: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
 ffff888101388800: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888101388880: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                            ^
 ffff888101388900: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
 ffff888101388980: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
==================================================================


***

KASAN: slab-use-after-free Read in dx_probe

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      70b672833f4025341c11b22c7f83778a5cd611bc
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/7b860156-1ca9-441f-b899-ebfb5a09620d/config
syz repro: https://ci.syzbot.org/findings/5524eff5-62fb-4cff-8d4e-7e3750aa921b/syz_repro

EXT4-fs (loop2): mounted filesystem 00000000-0000-0000-0000-000000000000 ro without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-use-after-free in ext4_dir_entry_is_tail fs/ext4/ext4.h:4001 [inline]
BUG: KASAN: slab-use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4024 [inline]
BUG: KASAN: slab-use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
BUG: KASAN: slab-use-after-free in dx_root_limit fs/ext4/namei.c:583 [inline]
BUG: KASAN: slab-use-after-free in dx_probe+0x1ac9/0x1d90 fs/ext4/namei.c:861
Read of size 4 at addr ffff888109c42c10 by task syz.2.20/5984

CPU: 0 UID: 0 PID: 5984 Comm: syz.2.20 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dir_entry_is_tail fs/ext4/ext4.h:4001 [inline]
 ext4_dirent_get_data_len fs/ext4/ext4.h:4024 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
 dx_root_limit fs/ext4/namei.c:583 [inline]
 dx_probe+0x1ac9/0x1d90 fs/ext4/namei.c:861
 ext4_dx_find_entry fs/ext4/namei.c:1812 [inline]
 __ext4_find_entry+0x5a9/0x2140 fs/ext4/namei.c:1652
 ext4_lookup_entry fs/ext4/namei.c:1794 [inline]
 ext4_lookup+0x17b/0x710 fs/ext4/namei.c:1860
 lookup_open fs/namei.c:4456 [inline]
 open_last_lookups fs/namei.c:4583 [inline]
 path_openat+0x11ac/0x3860 fs/namei.c:4827
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb97dd9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb97ec96028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fb97e015fa0 RCX: 00007fb97dd9c819
RDX: 0000000000042041 RSI: 0000200000000700 RDI: ffffffffffffff9c
RBP: 00007fb97de32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000001d R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb97e016038 R14: 00007fb97e015fa0 R15: 00007fffcac5f5a8
 </TASK>

Allocated by task 5828:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5260 [inline]
 __kmalloc_noprof+0x35c/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
 tomoyo_path_symlink+0xab/0xf0 security/tomoyo/tomoyo.c:212
 security_path_symlink+0x16f/0x360 security/security.c:1477
 filename_symlinkat+0x134/0x410 fs/namei.c:5638
 __do_sys_symlink fs/namei.c:5667 [inline]
 __se_sys_symlink+0x4d/0x2b0 fs/namei.c:5663
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5828:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2685 [inline]
 slab_free mm/slub.c:6165 [inline]
 kfree+0x1c1/0x630 mm/slub.c:6483
 tomoyo_realpath_from_path+0x598/0x5d0 security/tomoyo/realpath.c:286
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
 tomoyo_path_symlink+0xab/0xf0 security/tomoyo/tomoyo.c:212
 security_path_symlink+0x16f/0x360 security/security.c:1477
 filename_symlinkat+0x134/0x410 fs/namei.c:5638
 __do_sys_symlink fs/namei.c:5667 [inline]
 __se_sys_symlink+0x4d/0x2b0 fs/namei.c:5663
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888109c42000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 3088 bytes inside of
 freed 4096-byte region [ffff888109c42000, ffff888109c43000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x109c40
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000040 ffff888100042140 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
head: 017ff00000000040 ffff888100042140 dead000000000100 dead000000000122
head: 0000000000000000 0000000800040004 00000000f5000000 0000000000000000
head: 017ff00000000003 ffffea0004271001 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5828, tgid 5828 (udevd), ts 67573015608, free_ts 47549723112
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x283/0x560 security/tomoyo/file.c:827
 tomoyo_path_symlink+0xab/0xf0 security/tomoyo/tomoyo.c:212
 security_path_symlink+0x16f/0x360 security/security.c:1477
 filename_symlinkat+0x134/0x410 fs/namei.c:5638
 __do_sys_symlink fs/namei.c:5667 [inline]
 __se_sys_symlink+0x4d/0x2b0 fs/namei.c:5663
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5718 tgid 5718 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 __slab_free+0x263/0x2b0 mm/slub.c:5573
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4538 [inline]
 slab_alloc_node mm/slub.c:4866 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4873
 alloc_filename fs/namei.c:142 [inline]
 do_getname+0x2e/0x250 fs/namei.c:182
 getname include/linux/fs.h:2512 [inline]
 getname_maybe_null include/linux/fs.h:2519 [inline]
 class_filename_maybe_null_constructor include/linux/fs.h:2543 [inline]
 vfs_fstatat+0x45/0x170 fs/stat.c:368
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat fs/stat.c:532 [inline]
 __x64_sys_newfstatat+0x151/0x200 fs/stat.c:532
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888109c42b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888109c42b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888109c42c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888109c42c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888109c42d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


***

KASAN: use-after-free Read in __ext4_check_dir_entry

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      70b672833f4025341c11b22c7f83778a5cd611bc
arch:      amd64
compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config:    https://ci.syzbot.org/builds/7b860156-1ca9-441f-b899-ebfb5a09620d/config
syz repro: https://ci.syzbot.org/findings/21333690-a422-407b-92c7-9247a0075b74/syz_repro

loop1: lost filesystem error report for type 5 error -117
EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: use-after-free in ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
BUG: KASAN: use-after-free in ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
Read of size 1 at addr ffff88810da3609c by task syz.1.20/5966

CPU: 0 UID: 0 PID: 5966 Comm: syz.1.20 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_dirent_get_data_len fs/ext4/ext4.h:4040 [inline]
 ext4_dir_entry_len fs/ext4/ext4.h:4060 [inline]
 __ext4_check_dir_entry+0x527/0xa70 fs/ext4/dir.c:96
 ext4_inlinedir_to_tree+0x6be/0xbf0 fs/ext4/inline.c:1322
 ext4_htree_fill_tree+0x50b/0x1230 fs/ext4/namei.c:1184
 ext4_dx_readdir fs/ext4/dir.c:600 [inline]
 ext4_readdir+0x2f7b/0x3870 fs/ext4/dir.c:146
 iterate_dir+0x399/0x570 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:412 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:397
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb82a19c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb82b01a028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fb82a415fa0 RCX: 00007fb82a19c819
RDX: 000000000000ff80 RSI: 9999999999999999 RDI: 0000000000000004
RBP: 00007fb82a232c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb82a416038 R14: 00007fb82a415fa0 R15: 00007ffdc30464e8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88810da36000 pfn:0x10da36
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 017ff00000000000 ffffea0004364708 ffffea000436a7c8 0000000000000000
raw: ffff88810da36000 0000000000000000 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2c00(GFP_NOIO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 15037633903, free_ts 26770192426
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3292 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3481
 new_slab mm/slub.c:3539 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7175
 refill_sheaf mm/slub.c:2812 [inline]
 __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
 alloc_from_pcs mm/slub.c:4717 [inline]
 slab_alloc_node mm/slub.c:4851 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5272
 kmalloc_noprof include/linux/slab.h:954 [inline]
 usb_alloc_urb+0x46/0x150 drivers/usb/core/urb.c:75
 usb_internal_control_msg drivers/usb/core/message.c:110 [inline]
 usb_control_msg+0x118/0x3e0 drivers/usb/core/message.c:167
 usb_get_descriptor+0xb1/0x3e0 drivers/usb/core/message.c:852
 usb_get_configuration+0x3b9/0x54f0 drivers/usb/core/config.c:986
 usb_enumerate_device drivers/usb/core/hub.c:2527 [inline]
 usb_new_device+0x145/0x16f0 drivers/usb/core/hub.c:2665
 register_root_hub+0x270/0x5f0 drivers/usb/core/hcd.c:990
 usb_add_hcd+0xba1/0x10b0 drivers/usb/core/hcd.c:2987
 vhci_hcd_probe+0x1fa/0x3e0 drivers/usb/usbip/vhci_hcd.c:1401
 platform_probe+0xf9/0x190 drivers/base/platform.c:1418
page last free pid 5262 tgid 5262 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
 __slab_free+0x263/0x2b0 mm/slub.c:5573
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4538 [inline]
 slab_alloc_node mm/slub.c:4866 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4873
 alloc_empty_file+0x55/0x1d0 fs/file_table.c:237
 path_openat+0x10f/0x3860 fs/namei.c:4816
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88810da35f80: 00 00 00 00 00 00 00 04 fc fc fc fc fc fc fc fc
 ffff88810da36000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88810da36080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88810da36100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88810da36180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@syzkaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.

To test a patch for this bug, please reply with `#syz test`
(should be on a separate line).

The patch should be attached to the email.
Note: arguments like custom git repos and branches are not supported.

[-- Attachment #1.2: Type: text/html, Size: 53647 bytes --]

[-- Attachment #2: 0001-ext4-fix-syzbot.patch --]
[-- Type: application/octet-stream, Size: 4000 bytes --]

From 18df6683799e259479dc53260e59b5d1fdc6a143 Mon Sep 17 00:00:00 2001
From: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Date: Sat, 18 Apr 2026 17:33:23 -0400
Subject: [PATCH] ext4: fix syzbot

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
---
 fs/ext4/ext4.h   | 33 ++++++++++++++++++++++++++++-----
 fs/ext4/inline.c |  8 +++++++-
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 28271d42bfaf..c5d4aaed8e6e 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -4007,6 +4007,7 @@ static inline bool ext4_dir_entry_is_tail(struct ext4_dir_entry_2 *de)
 /*
  * ext4_dirent_get_data_len() - Compute the total dirdata length for an entry.
  * @de: directory entry
+ * @rec_len: the record length of the directory entry (decoded)
  *
  * Computes the length of optional data stored after the filename (and its
  * implicit NUL terminator).  Each extension is indicated by a bit in the
@@ -4015,21 +4016,39 @@ static inline bool ext4_dir_entry_is_tail(struct ext4_dir_entry_2 *de)
  *
  * Returns 0 for tail entries and for entries with no dirdata.
  */
-static inline int ext4_dirent_get_data_len(struct ext4_dir_entry_2 *de)
+static inline int ext4_dirent_get_data_len(struct ext4_dir_entry_2 *de,
+					   unsigned int rec_len)
 {
 	__u8 extra_data_flags;
 	struct ext4_dirent_data_header *ddh;
 	int dlen = 0;
+	unsigned int offset;
 
 	if (ext4_dir_entry_is_tail(de))
 		return 0;
 
 	extra_data_flags = (de->file_type & ~EXT4_FT_MASK) >> 4;
-	ddh = (struct ext4_dirent_data_header *)(de->name + de->name_len +
-						 1 /* NUL terminator */);
+	/* offset from start of entry to after filename + NUL */
+	offset = EXT4_BASE_DIR_LEN + de->name_len + 1;
+
+	/* bounds check: ensure we start reading within the entry */
+	if (offset >= rec_len)
+		return 0;
+
+	ddh = (struct ext4_dirent_data_header *)((char *)de + offset);
 
 	while (extra_data_flags) {
 		if (extra_data_flags & 1) {
+			/* bounds check before reading ddh_length */
+			if (offset + sizeof(struct ext4_dirent_data_header) >
+			    rec_len)
+				return dlen;
+
+			/* validate ddh_length is reasonable */
+			if (ddh->ddh_length == 0 || ddh->ddh_length >
+			    rec_len - offset)
+				return dlen;
+
 			/*
 			 * The first dirdata field is preceded by a NUL
 			 * terminator byte that is already included in ddh's
@@ -4038,7 +4057,9 @@ static inline int ext4_dirent_get_data_len(struct ext4_dir_entry_2 *de)
 			if (dlen == 0)
 				dlen = 1; /* NUL terminator */
 			dlen += ddh->ddh_length;
-			ddh = ext4_dirdata_next(ddh);
+			offset += ddh->ddh_length;
+			ddh = (struct ext4_dirent_data_header *)
+					((char *)ddh + ddh->ddh_length);
 		}
 		extra_data_flags >>= 1;
 	}
@@ -4057,7 +4078,9 @@ static inline int ext4_dirent_get_data_len(struct ext4_dir_entry_2 *de)
 static inline unsigned int ext4_dir_entry_len(struct ext4_dir_entry_2 *de,
 					      const struct inode *dir)
 {
-	unsigned int dirdata = ext4_dirent_get_data_len(de);
+	unsigned int blocksize = (dir && dir->i_sb) ? dir->i_sb->s_blocksize : 4096;
+	unsigned int rec_len = ext4_rec_len_from_disk(de->rec_len, blocksize);
+	unsigned int dirdata = ext4_dirent_get_data_len(de, rec_len);
 
 	return ext4_dirent_rec_len(de->name_len + dirdata, dir);
 }
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 071a637c8869..709acbf5e198 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -1318,7 +1318,13 @@ int ext4_inlinedir_to_tree(struct file *dir_file,
 			pos = EXT4_INLINE_DOTDOT_SIZE;
 		} else {
 			de = (struct ext4_dir_entry_2 *)(dir_buf + pos);
-			pos += ext4_rec_len_from_disk(de->rec_len, inline_size);
+			/* Use ext4_dir_entry_len to account for dirdata extensions */
+			pos += ext4_dir_entry_len(de, dir);
+			/* Validate pos doesn't exceed buffer to prevent use-after-free */
+			if (pos > inline_size) {
+				ret = count;
+				goto out;
+			}
 			if (ext4_check_dir_entry(inode, dir_file, de,
 					 iloc.bh, dir_buf,
 					 inline_size, pos)) {
-- 
2.43.7

[syzbot ci] Re: Data in direntry (dirdata) feature

[syzbot ci]

syzbot ci has tested the suggested fix patch on top of the following series:

[v1] Data in direntry (dirdata) feature
https://lore.kernel.org/all/20260417213723.74204-1-artem.blagodarenko@gmail.com

Patch: https://ci.syzbot.org/jobs/85bfb76c-4e56-4c94-a48e-da4f5b05ab28/patch
Testing results:
* [build 0] Build Patched: passed
* [build 0] Boot test: Patched: passed

Full report is available here:
https://ci.syzbot.org/session/3c8010c2-cb0e-4292-a935-ecb59d1a9d82

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.