[PATCH 4.19 1/5] staging: erofs: add error handling for xattr submodule

[PATCH 4.19 1/5] staging: erofs: add error handling for xattr submodule

[Gao Xiang]

commit cadf1ccf1b0021d0b7a9347e102ac5258f9f98c8 upstream.

This patch enhances the missing error handling code for
xattr submodule, which improves the stability for the rare cases.

Reviewed-by: Chao Yu <yuchao0 at huawei.com>
Signed-off-by: Chao Yu <yuchao0 at huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
---

This series resolves the following conflicts:
 FAILED: patch "[PATCH] staging: erofs: fix fast symlink w/o xattr when fs xattr is" failed to apply to 4.19-stable tree
 FAILED: patch "[PATCH] staging: erofs: fix memleak of inode's shared xattr array" failed to apply to 4.19-stable tree
 FAILED: patch "[PATCH] staging: erofs: fix race of initializing xattrs of a inode at" failed to apply to 4.19-stable tree
 FAILED: patch "[PATCH] staging: erofs: keep corrupted fs from crashing kernel in" failed to apply to 4.19-stable tree

In addition, there is another patch called
 staging: erofs: add error handling for xattr submodule
that needs to be backported to 4.19 as well (4.20+ already has this patch.)

 drivers/staging/erofs/internal.h |   5 +-
 drivers/staging/erofs/xattr.c    | 112 +++++++++++++++++++++++++++------------
 2 files changed, 81 insertions(+), 36 deletions(-)

diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index 9f44ed8f0023..1c048c412fb2 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -485,8 +485,9 @@ struct erofs_map_blocks_iter {
 };
 
 
-static inline struct page *erofs_get_inline_page(struct inode *inode,
-	erofs_blk_t blkaddr)
+static inline struct page *
+erofs_get_inline_page(struct inode *inode,
+		      erofs_blk_t blkaddr)
 {
 	return erofs_get_meta_page(inode->i_sb,
 		blkaddr, S_ISDIR(inode->i_mode));
diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
index 0e9cfeccdf99..d4bccb57e7c3 100644
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -24,16 +24,25 @@ struct xattr_iter {
 
 static inline void xattr_iter_end(struct xattr_iter *it, bool atomic)
 {
-	/* only init_inode_xattrs use non-atomic once */
+	/* the only user of kunmap() is 'init_inode_xattrs' */
 	if (unlikely(!atomic))
 		kunmap(it->page);
 	else
 		kunmap_atomic(it->kaddr);
+
 	unlock_page(it->page);
 	put_page(it->page);
 }
 
-static void init_inode_xattrs(struct inode *inode)
+static inline void xattr_iter_end_final(struct xattr_iter *it)
+{
+	if (!it->page)
+		return;
+
+	xattr_iter_end(it, true);
+}
+
+static int init_inode_xattrs(struct inode *inode)
 {
 	struct xattr_iter it;
 	unsigned i;
@@ -43,7 +52,7 @@ static void init_inode_xattrs(struct inode *inode)
 	bool atomic_map;
 
 	if (likely(inode_has_inited_xattr(inode)))
-		return;
+		return 0;
 
 	vi = EROFS_V(inode);
 	BUG_ON(!vi->xattr_isize);
@@ -53,7 +62,8 @@ static void init_inode_xattrs(struct inode *inode)
 	it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);
 
 	it.page = erofs_get_inline_page(inode, it.blkaddr);
-	BUG_ON(IS_ERR(it.page));
+	if (IS_ERR(it.page))
+		return PTR_ERR(it.page);
 
 	/* read in shared xattr array (non-atomic, see kmalloc below) */
 	it.kaddr = kmap(it.page);
@@ -62,9 +72,12 @@ static void init_inode_xattrs(struct inode *inode)
 	ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
 
 	vi->xattr_shared_count = ih->h_shared_count;
-	vi->xattr_shared_xattrs = (unsigned *)kmalloc_array(
-		vi->xattr_shared_count, sizeof(unsigned),
-		GFP_KERNEL | __GFP_NOFAIL);
+	vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
+						sizeof(uint), GFP_KERNEL);
+	if (!vi->xattr_shared_xattrs) {
+		xattr_iter_end(&it, atomic_map);
+		return -ENOMEM;
+	}
 
 	/* let's skip ibody header */
 	it.ofs += sizeof(struct erofs_xattr_ibody_header);
@@ -77,7 +90,8 @@ static void init_inode_xattrs(struct inode *inode)
 
 			it.page = erofs_get_meta_page(inode->i_sb,
 				++it.blkaddr, S_ISDIR(inode->i_mode));
-			BUG_ON(IS_ERR(it.page));
+			if (IS_ERR(it.page))
+				return PTR_ERR(it.page);
 
 			it.kaddr = kmap_atomic(it.page);
 			atomic_map = true;
@@ -90,6 +104,7 @@ static void init_inode_xattrs(struct inode *inode)
 	xattr_iter_end(&it, atomic_map);
 
 	inode_set_inited_xattr(inode);
+	return 0;
 }
 
 struct xattr_iter_handlers {
@@ -99,18 +114,25 @@ struct xattr_iter_handlers {
 	void (*value)(struct xattr_iter *, unsigned, char *, unsigned);
 };
 
-static void xattr_iter_fixup(struct xattr_iter *it)
+static inline int xattr_iter_fixup(struct xattr_iter *it)
 {
-	if (unlikely(it->ofs >= EROFS_BLKSIZ)) {
-		xattr_iter_end(it, true);
+	if (it->ofs < EROFS_BLKSIZ)
+		return 0;
 
-		it->blkaddr += erofs_blknr(it->ofs);
-		it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
-		BUG_ON(IS_ERR(it->page));
+	xattr_iter_end(it, true);
 
-		it->kaddr = kmap_atomic(it->page);
-		it->ofs = erofs_blkoff(it->ofs);
+	it->blkaddr += erofs_blknr(it->ofs);
+	it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
+	if (IS_ERR(it->page)) {
+		int err = PTR_ERR(it->page);
+
+		it->page = NULL;
+		return err;
 	}
+
+	it->kaddr = kmap_atomic(it->page);
+	it->ofs = erofs_blkoff(it->ofs);
+	return 0;
 }
 
 static int inline_xattr_iter_begin(struct xattr_iter *it,
@@ -132,21 +154,24 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
 	it->ofs = erofs_blkoff(iloc(sbi, vi->nid) + inline_xattr_ofs);
 
 	it->page = erofs_get_inline_page(inode, it->blkaddr);
-	BUG_ON(IS_ERR(it->page));
-	it->kaddr = kmap_atomic(it->page);
+	if (IS_ERR(it->page))
+		return PTR_ERR(it->page);
 
+	it->kaddr = kmap_atomic(it->page);
 	return vi->xattr_isize - xattr_header_sz;
 }
 
 static int xattr_foreach(struct xattr_iter *it,
-	struct xattr_iter_handlers *op, unsigned *tlimit)
+	const struct xattr_iter_handlers *op, unsigned int *tlimit)
 {
 	struct erofs_xattr_entry entry;
 	unsigned value_sz, processed, slice;
 	int err;
 
 	/* 0. fixup blkaddr, ofs, ipage */
-	xattr_iter_fixup(it);
+	err = xattr_iter_fixup(it);
+	if (err)
+		return err;
 
 	/*
 	 * 1. read xattr entry to the memory,
@@ -178,7 +203,9 @@ static int xattr_foreach(struct xattr_iter *it,
 		if (it->ofs >= EROFS_BLKSIZ) {
 			BUG_ON(it->ofs > EROFS_BLKSIZ);
 
-			xattr_iter_fixup(it);
+			err = xattr_iter_fixup(it);
+			if (err)
+				goto out;
 			it->ofs = 0;
 		}
 
@@ -210,7 +237,10 @@ static int xattr_foreach(struct xattr_iter *it,
 	while (processed < value_sz) {
 		if (it->ofs >= EROFS_BLKSIZ) {
 			BUG_ON(it->ofs > EROFS_BLKSIZ);
-			xattr_iter_fixup(it);
+
+			err = xattr_iter_fixup(it);
+			if (err)
+				goto out;
 			it->ofs = 0;
 		}
 
@@ -270,7 +300,7 @@ static void xattr_copyvalue(struct xattr_iter *_it,
 	memcpy(it->buffer + processed, buf, len);
 }
 
-static struct xattr_iter_handlers find_xattr_handlers = {
+static const struct xattr_iter_handlers find_xattr_handlers = {
 	.entry = xattr_entrymatch,
 	.name = xattr_namematch,
 	.alloc_buffer = xattr_checkbuffer,
@@ -291,8 +321,11 @@ static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
 		ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining);
 		if (ret >= 0)
 			break;
+
+		if (ret != -ENOATTR)	/* -ENOMEM, -EIO, etc. */
+			break;
 	}
-	xattr_iter_end(&it->it, true);
+	xattr_iter_end_final(&it->it);
 
 	return ret < 0 ? ret : it->buffer_size;
 }
@@ -315,8 +348,10 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
 				xattr_iter_end(&it->it, true);
 
 			it->it.page = erofs_get_meta_page(inode->i_sb,
-				blkaddr, false);
-			BUG_ON(IS_ERR(it->it.page));
+							  blkaddr, false);
+			if (IS_ERR(it->it.page))
+				return PTR_ERR(it->it.page);
+
 			it->it.kaddr = kmap_atomic(it->it.page);
 			it->it.blkaddr = blkaddr;
 		}
@@ -324,9 +359,12 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
 		ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
 		if (ret >= 0)
 			break;
+
+		if (ret != -ENOATTR)	/* -ENOMEM, -EIO, etc. */
+			break;
 	}
 	if (vi->xattr_shared_count)
-		xattr_iter_end(&it->it, true);
+		xattr_iter_end_final(&it->it);
 
 	return ret < 0 ? ret : it->buffer_size;
 }
@@ -351,7 +389,9 @@ int erofs_getxattr(struct inode *inode, int index,
 	if (unlikely(name == NULL))
 		return -EINVAL;
 
-	init_inode_xattrs(inode);
+	ret = init_inode_xattrs(inode);
+	if (ret)
+		return ret;
 
 	it.index = index;
 
@@ -494,7 +534,7 @@ static int xattr_skipvalue(struct xattr_iter *_it,
 	return 1;
 }
 
-static struct xattr_iter_handlers list_xattr_handlers = {
+static const struct xattr_iter_handlers list_xattr_handlers = {
 	.entry = xattr_entrylist,
 	.name = xattr_namelist,
 	.alloc_buffer = xattr_skipvalue,
@@ -516,7 +556,7 @@ static int inline_listxattr(struct listxattr_iter *it)
 		if (ret < 0)
 			break;
 	}
-	xattr_iter_end(&it->it, true);
+	xattr_iter_end_final(&it->it);
 	return ret < 0 ? ret : it->buffer_ofs;
 }
 
@@ -538,8 +578,10 @@ static int shared_listxattr(struct listxattr_iter *it)
 				xattr_iter_end(&it->it, true);
 
 			it->it.page = erofs_get_meta_page(inode->i_sb,
-				blkaddr, false);
-			BUG_ON(IS_ERR(it->it.page));
+							  blkaddr, false);
+			if (IS_ERR(it->it.page))
+				return PTR_ERR(it->it.page);
+
 			it->it.kaddr = kmap_atomic(it->it.page);
 			it->it.blkaddr = blkaddr;
 		}
@@ -549,7 +591,7 @@ static int shared_listxattr(struct listxattr_iter *it)
 			break;
 	}
 	if (vi->xattr_shared_count)
-		xattr_iter_end(&it->it, true);
+		xattr_iter_end_final(&it->it);
 
 	return ret < 0 ? ret : it->buffer_ofs;
 }
@@ -560,7 +602,9 @@ ssize_t erofs_listxattr(struct dentry *dentry,
 	int ret;
 	struct listxattr_iter it;
 
-	init_inode_xattrs(d_inode(dentry));
+	ret = init_inode_xattrs(d_inode(dentry));
+	if (ret)
+		return ret;
 
 	it.dentry = dentry;
 	it.buffer = buffer;
-- 
2.14.5

[PATCH 4.19 2/5] staging: erofs: fix fast symlink w/o xattr when fs xattr is on

[Gao Xiang]

commit 7077fffcb0b0b65dc75e341306aeef4d0e7f2ec6 upstream.

Currently, this will hit a BUG_ON for these symlinks as follows:

- kernel message
------------[ cut here ]------------
kernel BUG at drivers/staging/erofs/xattr.c:59!
SMP PTI
CPU: 1 PID: 1170 Comm: getllxattr Not tainted 4.20.0-rc6+ #92
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-2.fc27 04/01/2014
RIP: 0010:init_inode_xattrs+0x22b/0x270
Code: 48 0f 45 ea f0 ff 4d 34 74 0d 41 83 4c 24 e0 01 31 c0 e9 00 fe ff ff 48 89 ef e8 e0 31 9e ff eb e9 89 e8 e9 ef fd ff ff 0f 0$
 <0f> 0b 48 89 ef e8 fb f6 9c ff 48 8b 45 08 a8 01 75 24 f0 ff 4d 34
RSP: 0018:ffffa03ac026bdf8 EFLAGS: 00010246
------------[ cut here ]------------
...
Call Trace:
 erofs_listxattr+0x30/0x2c0
 ? selinux_inode_listxattr+0x5a/0x80
 ? kmem_cache_alloc+0x33/0x170
 ? security_inode_listxattr+0x27/0x40
 listxattr+0xaf/0xc0
 path_listxattr+0x5a/0xa0
 do_syscall_64+0x43/0xf0
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
...
---[ end trace 3c24b49408dc0c72 ]---

Fix it by checking ->xattr_isize in init_inode_xattrs(),
and it also fixes improper return value -ENOTSUPP
(it should be -ENODATA if xattr is enabled) for those inodes.

Fixes: b17500a0fdba ("staging: erofs: introduce xattr & acl support")
Cc: <stable at vger.kernel.org> # 4.19+
Reported-by: Li Guifu <bluce.liguifu at huawei.com>
Tested-by: Li Guifu <bluce.liguifu at huawei.com>
Reviewed-by: Chao Yu <yuchao0 at huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
---
 drivers/staging/erofs/inode.c |  8 ++++----
 drivers/staging/erofs/xattr.c | 25 ++++++++++++++++++++-----
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/drivers/staging/erofs/inode.c b/drivers/staging/erofs/inode.c
index 9e7815f55a17..7448744cc515 100644
--- a/drivers/staging/erofs/inode.c
+++ b/drivers/staging/erofs/inode.c
@@ -184,16 +184,16 @@ static int fill_inode(struct inode *inode, int isdir)
 		/* setup the new inode */
 		if (S_ISREG(inode->i_mode)) {
 #ifdef CONFIG_EROFS_FS_XATTR
-			if (vi->xattr_isize)
-				inode->i_op = &erofs_generic_xattr_iops;
+			inode->i_op = &erofs_generic_xattr_iops;
 #endif
 			inode->i_fop = &generic_ro_fops;
 		} else if (S_ISDIR(inode->i_mode)) {
 			inode->i_op =
 #ifdef CONFIG_EROFS_FS_XATTR
-				vi->xattr_isize ? &erofs_dir_xattr_iops :
-#endif
+				&erofs_dir_xattr_iops;
+#else
 				&erofs_dir_iops;
+#endif
 			inode->i_fop = &erofs_dir_fops;
 		} else if (S_ISLNK(inode->i_mode)) {
 			/* by default, page_get_link is used for symlink */
diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
index d4bccb57e7c3..ac2567576335 100644
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -55,7 +55,26 @@ static int init_inode_xattrs(struct inode *inode)
 		return 0;
 
 	vi = EROFS_V(inode);
-	BUG_ON(!vi->xattr_isize);
+
+	/*
+	 * bypass all xattr operations if ->xattr_isize is not greater than
+	 * sizeof(struct erofs_xattr_ibody_header), in detail:
+	 * 1) it is not enough to contain erofs_xattr_ibody_header then
+	 *    ->xattr_isize should be 0 (it means no xattr);
+	 * 2) it is just to contain erofs_xattr_ibody_header, which is on-disk
+	 *    undefined right now (maybe use later with some new sb feature).
+	 */
+	if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) {
+		errln("xattr_isize %d of nid %llu is not supported yet",
+		      vi->xattr_isize, vi->nid);
+		return -ENOTSUPP;
+	} else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {
+		if (unlikely(vi->xattr_isize)) {
+			DBG_BUGON(1);
+			return -EIO;	/* xattr ondisk layout error */
+		}
+		return -ENOATTR;
+	}
 
 	sbi = EROFS_I_SB(inode);
 	it.blkaddr = erofs_blknr(iloc(sbi, vi->nid) + vi->inode_isize);
@@ -414,7 +433,6 @@ static int erofs_xattr_generic_get(const struct xattr_handler *handler,
 		struct dentry *unused, struct inode *inode,
 		const char *name, void *buffer, size_t size)
 {
-	struct erofs_vnode *const vi = EROFS_V(inode);
 	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 
 	switch (handler->flags) {
@@ -432,9 +450,6 @@ static int erofs_xattr_generic_get(const struct xattr_handler *handler,
 		return -EINVAL;
 	}
 
-	if (!vi->xattr_isize)
-		return -ENOATTR;
-
 	return erofs_getxattr(inode, handler->flags, name, buffer, size);
 }
 
-- 
2.14.5

[PATCH 4.19 3/5] staging: erofs: fix memleak of inode's shared xattr array

[Gao Xiang]

From: Sheng Yong <shengyong1@huawei.com>

commit 3b1b5291f79d040d549d7c746669fc30e8045b9b upstream.

If it fails to read a shared xattr page, the inode's shared xattr array
is not freed. The next time the inode's xattr is accessed, the previously
allocated array is leaked.

Signed-off-by: Sheng Yong <shengyong1 at huawei.com>
Fixes: b17500a0fdba ("staging: erofs: introduce xattr & acl support")
Cc: <stable at vger.kernel.org> # 4.19+
Reviewed-by: Gao Xiang <gaoxiang25 at huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
---
 drivers/staging/erofs/xattr.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
index ac2567576335..890fa06bbcbb 100644
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -109,8 +109,11 @@ static int init_inode_xattrs(struct inode *inode)
 
 			it.page = erofs_get_meta_page(inode->i_sb,
 				++it.blkaddr, S_ISDIR(inode->i_mode));
-			if (IS_ERR(it.page))
+			if (IS_ERR(it.page)) {
+				kfree(vi->xattr_shared_xattrs);
+				vi->xattr_shared_xattrs = NULL;
 				return PTR_ERR(it.page);
+			}
 
 			it.kaddr = kmap_atomic(it.page);
 			atomic_map = true;
-- 
2.14.5

[PATCH 4.19 4/5] staging: erofs: fix race of initializing xattrs of a inode at the same time

[Gao Xiang]

commit 62dc45979f3f8cb0ea67302a93bff686f0c46c5a upstream.

In real scenario, there could be several threads accessing xattrs
of the same xattr-uninitialized inode, and init_inode_xattrs()
almost at the same time.

That's actually an unexpected behavior, this patch closes the race.

Fixes: b17500a0fdba ("staging: erofs: introduce xattr & acl support")
Cc: <stable at vger.kernel.org> # 4.19+
Reviewed-by: Chao Yu <yuchao0 at huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
---
 drivers/staging/erofs/internal.h | 11 ++++++++---
 drivers/staging/erofs/xattr.c    | 41 ++++++++++++++++++++++++++++------------
 2 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
index 1c048c412fb2..c70f0c5237ea 100644
--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -327,12 +327,17 @@ static inline erofs_off_t iloc(struct erofs_sb_info *sbi, erofs_nid_t nid)
 	return blknr_to_addr(sbi->meta_blkaddr) + (nid << sbi->islotbits);
 }
 
-#define inode_set_inited_xattr(inode)   (EROFS_V(inode)->flags |= 1)
-#define inode_has_inited_xattr(inode)   (EROFS_V(inode)->flags & 1)
+/* atomic flag definitions */
+#define EROFS_V_EA_INITED_BIT	0
+
+/* bitlock definitions (arranged in reverse order) */
+#define EROFS_V_BL_XATTR_BIT	(BITS_PER_LONG - 1)
 
 struct erofs_vnode {
 	erofs_nid_t nid;
-	unsigned int flags;
+
+	/* atomic flags (including bitlocks) */
+	unsigned long flags;
 
 	unsigned char data_mapping_mode;
 	/* inline size in bytes */
diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c
index 890fa06bbcbb..955d024bf5a9 100644
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -44,17 +44,24 @@ static inline void xattr_iter_end_final(struct xattr_iter *it)
 
 static int init_inode_xattrs(struct inode *inode)
 {
+	struct erofs_vnode *const vi = EROFS_V(inode);
 	struct xattr_iter it;
 	unsigned i;
 	struct erofs_xattr_ibody_header *ih;
 	struct erofs_sb_info *sbi;
-	struct erofs_vnode *vi;
 	bool atomic_map;
+	int ret = 0;
 
-	if (likely(inode_has_inited_xattr(inode)))
+	/* the most case is that xattrs of this inode are initialized. */
+	if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags))
 		return 0;
 
-	vi = EROFS_V(inode);
+	if (wait_on_bit_lock(&vi->flags, EROFS_V_BL_XATTR_BIT, TASK_KILLABLE))
+		return -ERESTARTSYS;
+
+	/* someone has initialized xattrs for us? */
+	if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags))
+		goto out_unlock;
 
 	/*
 	 * bypass all xattr operations if ->xattr_isize is not greater than
@@ -67,13 +74,16 @@ static int init_inode_xattrs(struct inode *inode)
 	if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) {
 		errln("xattr_isize %d of nid %llu is not supported yet",
 		      vi->xattr_isize, vi->nid);
-		return -ENOTSUPP;
+		ret = -ENOTSUPP;
+		goto out_unlock;
 	} else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {
 		if (unlikely(vi->xattr_isize)) {
 			DBG_BUGON(1);
-			return -EIO;	/* xattr ondisk layout error */
+			ret = -EIO;
+			goto out_unlock;	/* xattr ondisk layout error */
 		}
-		return -ENOATTR;
+		ret = -ENOATTR;
+		goto out_unlock;
 	}
 
 	sbi = EROFS_I_SB(inode);
@@ -81,8 +91,10 @@ static int init_inode_xattrs(struct inode *inode)
 	it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);
 
 	it.page = erofs_get_inline_page(inode, it.blkaddr);
-	if (IS_ERR(it.page))
-		return PTR_ERR(it.page);
+	if (IS_ERR(it.page)) {
+		ret = PTR_ERR(it.page);
+		goto out_unlock;
+	}
 
 	/* read in shared xattr array (non-atomic, see kmalloc below) */
 	it.kaddr = kmap(it.page);
@@ -95,7 +107,8 @@ static int init_inode_xattrs(struct inode *inode)
 						sizeof(uint), GFP_KERNEL);
 	if (vi->xattr_shared_xattrs == NULL) {
 		xattr_iter_end(&it, atomic_map);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto out_unlock;
 	}
 
 	/* let's skip ibody header */
@@ -112,7 +125,8 @@ static int init_inode_xattrs(struct inode *inode)
 			if (IS_ERR(it.page)) {
 				kfree(vi->xattr_shared_xattrs);
 				vi->xattr_shared_xattrs = NULL;
-				return PTR_ERR(it.page);
+				ret = PTR_ERR(it.page);
+				goto out_unlock;
 			}
 
 			it.kaddr = kmap_atomic(it.page);
@@ -125,8 +139,11 @@ static int init_inode_xattrs(struct inode *inode)
 	}
 	xattr_iter_end(&it, atomic_map);
 
-	inode_set_inited_xattr(inode);
-	return 0;
+	set_bit(EROFS_V_EA_INITED_BIT, &vi->flags);
+
+out_unlock:
+	clear_and_wake_up_bit(EROFS_V_BL_XATTR_BIT, &vi->flags);
+	return ret;
 }
 
 struct xattr_iter_handlers {
-- 
2.14.5

[PATCH 4.19 5/5] staging: erofs: keep corrupted fs from crashing kernel in erofs_namei()

[Gao Xiang]

commit 419d6efc50e94bcf5d6b35cd8c71f79edadec564 upstream.

As Al pointed out, "
... and while we are at it, what happens to
	unsigned int nameoff = le16_to_cpu(de[mid].nameoff);
	unsigned int matched = min(startprfx, endprfx);

	struct qstr dname = QSTR_INIT(data + nameoff,
		unlikely(mid >= ndirents - 1) ?
			maxsize - nameoff :
			le16_to_cpu(de[mid + 1].nameoff) - nameoff);

	/* string comparison without already matched prefix */
	int ret = dirnamecmp(name, &dname, &matched);
if le16_to_cpu(de[...].nameoff) is not monotonically increasing?  I.e.
what's to prevent e.g. (unsigned)-1 ending up in dname.len?

Corrupted fs image shouldn't oops the kernel.. "

Revisit the related lookup flow to address the issue.

Fixes: d72d1ce60174 ("staging: erofs: add namei functions")
Cc: <stable at vger.kernel.org> # 4.19+
Suggested-by: Al Viro <viro at ZenIV.linux.org.uk>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
---
 drivers/staging/erofs/namei.c | 189 ++++++++++++++++++++++--------------------
 1 file changed, 100 insertions(+), 89 deletions(-)

diff --git a/drivers/staging/erofs/namei.c b/drivers/staging/erofs/namei.c
index 546a47156101..023f64fa2c87 100644
--- a/drivers/staging/erofs/namei.c
+++ b/drivers/staging/erofs/namei.c
@@ -15,74 +15,77 @@
 
 #include <trace/events/erofs.h>
 
-/* based on the value of qn->len is accurate */
-static inline int dirnamecmp(struct qstr *qn,
-	struct qstr *qd, unsigned *matched)
+struct erofs_qstr {
+	const unsigned char *name;
+	const unsigned char *end;
+};
+
+/* based on the end of qn is accurate and it must have the trailing '\0' */
+static inline int dirnamecmp(const struct erofs_qstr *qn,
+			     const struct erofs_qstr *qd,
+			     unsigned int *matched)
 {
-	unsigned i = *matched, len = min(qn->len, qd->len);
-loop:
-	if (unlikely(i >= len)) {
-		*matched = i;
-		if (qn->len < qd->len) {
-			/*
-			 * actually (qn->len == qd->len)
-			 * when qd->name[i] == '\0'
-			 */
-			return qd->name[i] == '\0' ? 0 : -1;
+	unsigned int i = *matched;
+
+	/*
+	 * on-disk error, let's only BUG_ON in the debugging mode.
+	 * otherwise, it will return 1 to just skip the invalid name
+	 * and go on (in consideration of the lookup performance).
+	 */
+	DBG_BUGON(qd->name > qd->end);
+
+	/* qd could not have trailing '\0' */
+	/* However it is absolutely safe if < qd->end */
+	while (qd->name + i < qd->end && qd->name[i] != '\0') {
+		if (qn->name[i] != qd->name[i]) {
+			*matched = i;
+			return qn->name[i] > qd->name[i] ? 1 : -1;
 		}
-		return (qn->len > qd->len);
+		++i;
 	}
-
-	if (qn->name[i] != qd->name[i]) {
-		*matched = i;
-		return qn->name[i] > qd->name[i] ? 1 : -1;
-	}
-
-	++i;
-	goto loop;
+	*matched = i;
+	/* See comments in __d_alloc on the terminating NUL character */
+	return qn->name[i] == '\0' ? 0 : 1;
 }
 
-static struct erofs_dirent *find_target_dirent(
-	struct qstr *name,
-	u8 *data, int maxsize)
+#define nameoff_from_disk(off, sz)	(le16_to_cpu(off) & ((sz) - 1))
+
+static struct erofs_dirent *find_target_dirent(struct erofs_qstr *name,
+					       u8 *data,
+					       unsigned int dirblksize,
+					       const int ndirents)
 {
-	unsigned ndirents, head, back;
-	unsigned startprfx, endprfx;
+	int head, back;
+	unsigned int startprfx, endprfx;
 	struct erofs_dirent *const de = (struct erofs_dirent *)data;
 
-	/* make sure that maxsize is valid */
-	BUG_ON(maxsize < sizeof(struct erofs_dirent));
-
-	ndirents = le16_to_cpu(de->nameoff) / sizeof(*de);
-
-	/* corrupted dir (may be unnecessary...) */
-	BUG_ON(!ndirents);
-
-	head = 0;
+	/* since the 1st dirent has been evaluated previously */
+	head = 1;
 	back = ndirents - 1;
 	startprfx = endprfx = 0;
 
 	while (head <= back) {
-		unsigned mid = head + (back - head) / 2;
-		unsigned nameoff = le16_to_cpu(de[mid].nameoff);
-		unsigned matched = min(startprfx, endprfx);
-
-		struct qstr dname = QSTR_INIT(data + nameoff,
-			unlikely(mid >= ndirents - 1) ?
-				maxsize - nameoff :
-				le16_to_cpu(de[mid + 1].nameoff) - nameoff);
+		const int mid = head + (back - head) / 2;
+		const int nameoff = nameoff_from_disk(de[mid].nameoff,
+						      dirblksize);
+		unsigned int matched = min(startprfx, endprfx);
+		struct erofs_qstr dname = {
+			.name = data + nameoff,
+			.end = unlikely(mid >= ndirents - 1) ?
+				data + dirblksize :
+				data + nameoff_from_disk(de[mid + 1].nameoff,
+							 dirblksize)
+		};
 
 		/* string comparison without already matched prefix */
 		int ret = dirnamecmp(name, &dname, &matched);
 
-		if (unlikely(!ret))
+		if (unlikely(!ret)) {
 			return de + mid;
-		else if (ret > 0) {
+		} else if (ret > 0) {
 			head = mid + 1;
 			startprfx = matched;
-		} else if (unlikely(mid < 1))	/* fix "mid" overflow */
-			break;
-		else {
+		} else {
 			back = mid - 1;
 			endprfx = matched;
 		}
@@ -91,12 +94,12 @@ static struct erofs_dirent *find_target_dirent(
 	return ERR_PTR(-ENOENT);
 }
 
-static struct page *find_target_block_classic(
-	struct inode *dir,
-	struct qstr *name, int *_diff)
+static struct page *find_target_block_classic(struct inode *dir,
+					      struct erofs_qstr *name,
+					      int *_ndirents)
 {
-	unsigned startprfx, endprfx;
-	unsigned head, back;
+	unsigned int startprfx, endprfx;
+	int head, back;
 	struct address_space *const mapping = dir->i_mapping;
 	struct page *candidate = ERR_PTR(-ENOENT);
 
@@ -105,41 +108,43 @@ static struct page *find_target_block_classic(
 	back = inode_datablocks(dir) - 1;
 
 	while (head <= back) {
-		unsigned mid = head + (back - head) / 2;
+		const int mid = head + (back - head) / 2;
 		struct page *page = read_mapping_page(mapping, mid, NULL);
 
-		if (IS_ERR(page)) {
-exact_out:
-			if (!IS_ERR(candidate)) /* valid candidate */
-				put_page(candidate);
-			return page;
-		} else {
-			int diff;
-			unsigned ndirents, matched;
-			struct qstr dname;
+		if (!IS_ERR(page)) {
 			struct erofs_dirent *de = kmap_atomic(page);
-			unsigned nameoff = le16_to_cpu(de->nameoff);
-
-			ndirents = nameoff / sizeof(*de);
+			const int nameoff = nameoff_from_disk(de->nameoff,
+							      EROFS_BLKSIZ);
+			const int ndirents = nameoff / sizeof(*de);
+			int diff;
+			unsigned int matched;
+			struct erofs_qstr dname;
 
-			/* corrupted dir (should have one entry at least) */
-			BUG_ON(!ndirents || nameoff > PAGE_SIZE);
+			if (unlikely(!ndirents)) {
+				DBG_BUGON(1);
+				kunmap_atomic(de);
+				put_page(page);
+				page = ERR_PTR(-EIO);
+				goto out;
+			}
 
 			matched = min(startprfx, endprfx);
 
 			dname.name = (u8 *)de + nameoff;
-			dname.len = ndirents == 1 ?
-				/* since the rest of the last page is 0 */
-				EROFS_BLKSIZ - nameoff
-				: le16_to_cpu(de[1].nameoff) - nameoff;
+			if (ndirents == 1)
+				dname.end = (u8 *)de + EROFS_BLKSIZ;
+			else
+				dname.end = (u8 *)de +
+					nameoff_from_disk(de[1].nameoff,
+							  EROFS_BLKSIZ);
 
 			/* string comparison without already matched prefix */
 			diff = dirnamecmp(name, &dname, &matched);
 			kunmap_atomic(de);
 
 			if (unlikely(!diff)) {
-				*_diff = 0;
-				goto exact_out;
+				*_ndirents = 0;
+				goto out;
 			} else if (diff > 0) {
 				head = mid + 1;
 				startprfx = matched;
@@ -147,45 +152,51 @@ static struct page *find_target_block_classic(
 				if (likely(!IS_ERR(candidate)))
 					put_page(candidate);
 				candidate = page;
+				*_ndirents = ndirents;
 			} else {
 				put_page(page);
 
-				if (unlikely(mid < 1))	/* fix "mid" overflow */
-					break;
-
 				back = mid - 1;
 				endprfx = matched;
 			}
+			continue;
 		}
+out:		/* free if the candidate is valid */
+		if (!IS_ERR(candidate))
+			put_page(candidate);
+		return page;
 	}
-	*_diff = 1;
 	return candidate;
 }
 
 int erofs_namei(struct inode *dir,
-	struct qstr *name,
-	erofs_nid_t *nid, unsigned *d_type)
+		struct qstr *name,
+		erofs_nid_t *nid, unsigned int *d_type)
 {
-	int diff;
+	int ndirents;
 	struct page *page;
-	u8 *data;
+	void *data;
 	struct erofs_dirent *de;
+	struct erofs_qstr qn;
 
 	if (unlikely(!dir->i_size))
 		return -ENOENT;
 
-	diff = 1;
-	page = find_target_block_classic(dir, name, &diff);
+	qn.name = name->name;
+	qn.end = name->name + name->len;
+
+	ndirents = 0;
+	page = find_target_block_classic(dir, &qn, &ndirents);
 
 	if (unlikely(IS_ERR(page)))
 		return PTR_ERR(page);
 
 	data = kmap_atomic(page);
 	/* the target page has been mapped */
-	de = likely(diff) ?
-		/* since the rest of the last page is 0 */
-		find_target_dirent(name, data, EROFS_BLKSIZ) :
-		(struct erofs_dirent *)data;
+	if (ndirents)
+		de = find_target_dirent(&qn, data, EROFS_BLKSIZ, ndirents);
+	else
+		de = (struct erofs_dirent *)data;
 
 	if (likely(!IS_ERR(de))) {
 		*nid = le64_to_cpu(de->nid);
-- 
2.14.5

[PATCH 4.19 1/5] staging: erofs: add error handling for xattr submodule

[Greg Kroah-Hartman]

On Mon, Mar 11, 2019@02:08:54PM +0800, Gao Xiang wrote:
> commit cadf1ccf1b0021d0b7a9347e102ac5258f9f98c8 upstream.
> 
> This patch enhances the missing error handling code for
> xattr submodule, which improves the stability for the rare cases.
> 
> Reviewed-by: Chao Yu <yuchao0 at huawei.com>
> Signed-off-by: Chao Yu <yuchao0 at huawei.com>
> Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
> ---
> 
> This series resolves the following conflicts:
>  FAILED: patch "[PATCH] staging: erofs: fix fast symlink w/o xattr when fs xattr is" failed to apply to 4.19-stable tree
>  FAILED: patch "[PATCH] staging: erofs: fix memleak of inode's shared xattr array" failed to apply to 4.19-stable tree
>  FAILED: patch "[PATCH] staging: erofs: fix race of initializing xattrs of a inode at" failed to apply to 4.19-stable tree
>  FAILED: patch "[PATCH] staging: erofs: keep corrupted fs from crashing kernel in" failed to apply to 4.19-stable tree
> 
> In addition, there is another patch called
>  staging: erofs: add error handling for xattr submodule
> that needs to be backported to 4.19 as well (4.20+ already has this patch.)
> 
>  drivers/staging/erofs/internal.h |   5 +-
>  drivers/staging/erofs/xattr.c    | 112 +++++++++++++++++++++++++++------------
>  2 files changed, 81 insertions(+), 36 deletions(-)

All now queued up, thanks.

greg k-h

Patch "staging: erofs: fix fast symlink w/o xattr when fs xattr is on" has been added to the 4.19-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    staging: erofs: fix fast symlink w/o xattr when fs xattr is on

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     staging-erofs-fix-fast-symlink-w-o-xattr-when-fs-xattr-is-on.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Tue Mar 12 05:46:41 PDT 2019
From: Gao Xiang <gaoxiang25@huawei.com>
Date: Mon, 11 Mar 2019 14:08:55 +0800
Subject: staging: erofs: fix fast symlink w/o xattr when fs xattr is on
To: <stable at vger.kernel.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>, LKML <linux-kernel at vger.kernel.org>, <linux-erofs at lists.ozlabs.org>, Chao Yu <yuchao0 at huawei.com>, Chao Yu <chao at kernel.org>, Miao Xie <miaoxie at huawei.com>, Fang Wei <fangwei1 at huawei.com>, Gao Xiang <gaoxiang25 at huawei.com>
Message-ID: <20190311060858.28654-2-gaoxiang25 at huawei.com>

From: Gao Xiang <gaoxiang25@huawei.com>

commit 7077fffcb0b0b65dc75e341306aeef4d0e7f2ec6 upstream.

Currently, this will hit a BUG_ON for these symlinks as follows:

- kernel message
------------[ cut here ]------------
kernel BUG at drivers/staging/erofs/xattr.c:59!
SMP PTI
CPU: 1 PID: 1170 Comm: getllxattr Not tainted 4.20.0-rc6+ #92
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-2.fc27 04/01/2014
RIP: 0010:init_inode_xattrs+0x22b/0x270
Code: 48 0f 45 ea f0 ff 4d 34 74 0d 41 83 4c 24 e0 01 31 c0 e9 00 fe ff ff 48 89 ef e8 e0 31 9e ff eb e9 89 e8 e9 ef fd ff ff 0f 0$
 <0f> 0b 48 89 ef e8 fb f6 9c ff 48 8b 45 08 a8 01 75 24 f0 ff 4d 34
RSP: 0018:ffffa03ac026bdf8 EFLAGS: 00010246
------------[ cut here ]------------
...
Call Trace:
 erofs_listxattr+0x30/0x2c0
 ? selinux_inode_listxattr+0x5a/0x80
 ? kmem_cache_alloc+0x33/0x170
 ? security_inode_listxattr+0x27/0x40
 listxattr+0xaf/0xc0
 path_listxattr+0x5a/0xa0
 do_syscall_64+0x43/0xf0
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
...
---[ end trace 3c24b49408dc0c72 ]---

Fix it by checking ->xattr_isize in init_inode_xattrs(),
and it also fixes improper return value -ENOTSUPP
(it should be -ENODATA if xattr is enabled) for those inodes.

Fixes: b17500a0fdba ("staging: erofs: introduce xattr & acl support")
Cc: <stable at vger.kernel.org> # 4.19+
Reported-by: Li Guifu <bluce.liguifu at huawei.com>
Tested-by: Li Guifu <bluce.liguifu at huawei.com>
Reviewed-by: Chao Yu <yuchao0 at huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/staging/erofs/inode.c |    8 ++++----
 drivers/staging/erofs/xattr.c |   25 ++++++++++++++++++++-----
 2 files changed, 24 insertions(+), 9 deletions(-)

--- a/drivers/staging/erofs/inode.c
+++ b/drivers/staging/erofs/inode.c
@@ -184,16 +184,16 @@ static int fill_inode(struct inode *inod
 		/* setup the new inode */
 		if (S_ISREG(inode->i_mode)) {
 #ifdef CONFIG_EROFS_FS_XATTR
-			if (vi->xattr_isize)
-				inode->i_op = &erofs_generic_xattr_iops;
+			inode->i_op = &erofs_generic_xattr_iops;
 #endif
 			inode->i_fop = &generic_ro_fops;
 		} else if (S_ISDIR(inode->i_mode)) {
 			inode->i_op =
 #ifdef CONFIG_EROFS_FS_XATTR
-				vi->xattr_isize ? &erofs_dir_xattr_iops :
-#endif
+				&erofs_dir_xattr_iops;
+#else
 				&erofs_dir_iops;
+#endif
 			inode->i_fop = &erofs_dir_fops;
 		} else if (S_ISLNK(inode->i_mode)) {
 			/* by default, page_get_link is used for symlink */
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -55,7 +55,26 @@ static int init_inode_xattrs(struct inod
 		return 0;
 
 	vi = EROFS_V(inode);
-	BUG_ON(!vi->xattr_isize);
+
+	/*
+	 * bypass all xattr operations if ->xattr_isize is not greater than
+	 * sizeof(struct erofs_xattr_ibody_header), in detail:
+	 * 1) it is not enough to contain erofs_xattr_ibody_header then
+	 *    ->xattr_isize should be 0 (it means no xattr);
+	 * 2) it is just to contain erofs_xattr_ibody_header, which is on-disk
+	 *    undefined right now (maybe use later with some new sb feature).
+	 */
+	if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) {
+		errln("xattr_isize %d of nid %llu is not supported yet",
+		      vi->xattr_isize, vi->nid);
+		return -ENOTSUPP;
+	} else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {
+		if (unlikely(vi->xattr_isize)) {
+			DBG_BUGON(1);
+			return -EIO;	/* xattr ondisk layout error */
+		}
+		return -ENOATTR;
+	}
 
 	sbi = EROFS_I_SB(inode);
 	it.blkaddr = erofs_blknr(iloc(sbi, vi->nid) + vi->inode_isize);
@@ -414,7 +433,6 @@ static int erofs_xattr_generic_get(const
 		struct dentry *unused, struct inode *inode,
 		const char *name, void *buffer, size_t size)
 {
-	struct erofs_vnode *const vi = EROFS_V(inode);
 	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 
 	switch (handler->flags) {
@@ -432,9 +450,6 @@ static int erofs_xattr_generic_get(const
 		return -EINVAL;
 	}
 
-	if (!vi->xattr_isize)
-		return -ENOATTR;
-
 	return erofs_getxattr(inode, handler->flags, name, buffer, size);
 }
 


Patches currently in stable-queue which might be from gaoxiang25 at huawei.com are

queue-4.19/staging-erofs-fix-fast-symlink-w-o-xattr-when-fs-xattr-is-on.patch
queue-4.19/staging-erofs-fix-race-of-initializing-xattrs-of-a-inode-at-the-same-time.patch
queue-4.19/staging-erofs-add-error-handling-for-xattr-submodule.patch
queue-4.19/staging-erofs-keep-corrupted-fs-from-crashing-kernel-in-erofs_namei.patch
queue-4.19/staging-erofs-fix-memleak-of-inode-s-shared-xattr-array.patch

Patch "staging: erofs: add error handling for xattr submodule" has been added to the 4.19-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    staging: erofs: add error handling for xattr submodule

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     staging-erofs-add-error-handling-for-xattr-submodule.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Tue Mar 12 05:46:41 PDT 2019
From: Gao Xiang <gaoxiang25@huawei.com>
Date: Mon, 11 Mar 2019 14:08:54 +0800
Subject: staging: erofs: add error handling for xattr submodule
To: <stable at vger.kernel.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>, LKML <linux-kernel at vger.kernel.org>, <linux-erofs at lists.ozlabs.org>, Chao Yu <yuchao0 at huawei.com>, Chao Yu <chao at kernel.org>, Miao Xie <miaoxie at huawei.com>, Fang Wei <fangwei1 at huawei.com>, Gao Xiang <gaoxiang25 at huawei.com>
Message-ID: <20190311060858.28654-1-gaoxiang25 at huawei.com>

From: Gao Xiang <gaoxiang25@huawei.com>

commit cadf1ccf1b0021d0b7a9347e102ac5258f9f98c8 upstream.

This patch enhances the missing error handling code for
xattr submodule, which improves the stability for the rare cases.

Reviewed-by: Chao Yu <yuchao0 at huawei.com>
Signed-off-by: Chao Yu <yuchao0 at huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/staging/erofs/internal.h |    5 +
 drivers/staging/erofs/xattr.c    |  112 +++++++++++++++++++++++++++------------
 2 files changed, 81 insertions(+), 36 deletions(-)

--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -485,8 +485,9 @@ struct erofs_map_blocks_iter {
 };
 
 
-static inline struct page *erofs_get_inline_page(struct inode *inode,
-	erofs_blk_t blkaddr)
+static inline struct page *
+erofs_get_inline_page(struct inode *inode,
+		      erofs_blk_t blkaddr)
 {
 	return erofs_get_meta_page(inode->i_sb,
 		blkaddr, S_ISDIR(inode->i_mode));
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -24,16 +24,25 @@ struct xattr_iter {
 
 static inline void xattr_iter_end(struct xattr_iter *it, bool atomic)
 {
-	/* only init_inode_xattrs use non-atomic once */
+	/* the only user of kunmap() is 'init_inode_xattrs' */
 	if (unlikely(!atomic))
 		kunmap(it->page);
 	else
 		kunmap_atomic(it->kaddr);
+
 	unlock_page(it->page);
 	put_page(it->page);
 }
 
-static void init_inode_xattrs(struct inode *inode)
+static inline void xattr_iter_end_final(struct xattr_iter *it)
+{
+	if (!it->page)
+		return;
+
+	xattr_iter_end(it, true);
+}
+
+static int init_inode_xattrs(struct inode *inode)
 {
 	struct xattr_iter it;
 	unsigned i;
@@ -43,7 +52,7 @@ static void init_inode_xattrs(struct ino
 	bool atomic_map;
 
 	if (likely(inode_has_inited_xattr(inode)))
-		return;
+		return 0;
 
 	vi = EROFS_V(inode);
 	BUG_ON(!vi->xattr_isize);
@@ -53,7 +62,8 @@ static void init_inode_xattrs(struct ino
 	it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);
 
 	it.page = erofs_get_inline_page(inode, it.blkaddr);
-	BUG_ON(IS_ERR(it.page));
+	if (IS_ERR(it.page))
+		return PTR_ERR(it.page);
 
 	/* read in shared xattr array (non-atomic, see kmalloc below) */
 	it.kaddr = kmap(it.page);
@@ -62,9 +72,12 @@ static void init_inode_xattrs(struct ino
 	ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
 
 	vi->xattr_shared_count = ih->h_shared_count;
-	vi->xattr_shared_xattrs = (unsigned *)kmalloc_array(
-		vi->xattr_shared_count, sizeof(unsigned),
-		GFP_KERNEL | __GFP_NOFAIL);
+	vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
+						sizeof(uint), GFP_KERNEL);
+	if (!vi->xattr_shared_xattrs) {
+		xattr_iter_end(&it, atomic_map);
+		return -ENOMEM;
+	}
 
 	/* let's skip ibody header */
 	it.ofs += sizeof(struct erofs_xattr_ibody_header);
@@ -77,7 +90,8 @@ static void init_inode_xattrs(struct ino
 
 			it.page = erofs_get_meta_page(inode->i_sb,
 				++it.blkaddr, S_ISDIR(inode->i_mode));
-			BUG_ON(IS_ERR(it.page));
+			if (IS_ERR(it.page))
+				return PTR_ERR(it.page);
 
 			it.kaddr = kmap_atomic(it.page);
 			atomic_map = true;
@@ -90,6 +104,7 @@ static void init_inode_xattrs(struct ino
 	xattr_iter_end(&it, atomic_map);
 
 	inode_set_inited_xattr(inode);
+	return 0;
 }
 
 struct xattr_iter_handlers {
@@ -99,18 +114,25 @@ struct xattr_iter_handlers {
 	void (*value)(struct xattr_iter *, unsigned, char *, unsigned);
 };
 
-static void xattr_iter_fixup(struct xattr_iter *it)
+static inline int xattr_iter_fixup(struct xattr_iter *it)
 {
-	if (unlikely(it->ofs >= EROFS_BLKSIZ)) {
-		xattr_iter_end(it, true);
+	if (it->ofs < EROFS_BLKSIZ)
+		return 0;
 
-		it->blkaddr += erofs_blknr(it->ofs);
-		it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
-		BUG_ON(IS_ERR(it->page));
+	xattr_iter_end(it, true);
 
-		it->kaddr = kmap_atomic(it->page);
-		it->ofs = erofs_blkoff(it->ofs);
+	it->blkaddr += erofs_blknr(it->ofs);
+	it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
+	if (IS_ERR(it->page)) {
+		int err = PTR_ERR(it->page);
+
+		it->page = NULL;
+		return err;
 	}
+
+	it->kaddr = kmap_atomic(it->page);
+	it->ofs = erofs_blkoff(it->ofs);
+	return 0;
 }
 
 static int inline_xattr_iter_begin(struct xattr_iter *it,
@@ -132,21 +154,24 @@ static int inline_xattr_iter_begin(struc
 	it->ofs = erofs_blkoff(iloc(sbi, vi->nid) + inline_xattr_ofs);
 
 	it->page = erofs_get_inline_page(inode, it->blkaddr);
-	BUG_ON(IS_ERR(it->page));
-	it->kaddr = kmap_atomic(it->page);
+	if (IS_ERR(it->page))
+		return PTR_ERR(it->page);
 
+	it->kaddr = kmap_atomic(it->page);
 	return vi->xattr_isize - xattr_header_sz;
 }
 
 static int xattr_foreach(struct xattr_iter *it,
-	struct xattr_iter_handlers *op, unsigned *tlimit)
+	const struct xattr_iter_handlers *op, unsigned int *tlimit)
 {
 	struct erofs_xattr_entry entry;
 	unsigned value_sz, processed, slice;
 	int err;
 
 	/* 0. fixup blkaddr, ofs, ipage */
-	xattr_iter_fixup(it);
+	err = xattr_iter_fixup(it);
+	if (err)
+		return err;
 
 	/*
 	 * 1. read xattr entry to the memory,
@@ -178,7 +203,9 @@ static int xattr_foreach(struct xattr_it
 		if (it->ofs >= EROFS_BLKSIZ) {
 			BUG_ON(it->ofs > EROFS_BLKSIZ);
 
-			xattr_iter_fixup(it);
+			err = xattr_iter_fixup(it);
+			if (err)
+				goto out;
 			it->ofs = 0;
 		}
 
@@ -210,7 +237,10 @@ static int xattr_foreach(struct xattr_it
 	while (processed < value_sz) {
 		if (it->ofs >= EROFS_BLKSIZ) {
 			BUG_ON(it->ofs > EROFS_BLKSIZ);
-			xattr_iter_fixup(it);
+
+			err = xattr_iter_fixup(it);
+			if (err)
+				goto out;
 			it->ofs = 0;
 		}
 
@@ -270,7 +300,7 @@ static void xattr_copyvalue(struct xattr
 	memcpy(it->buffer + processed, buf, len);
 }
 
-static struct xattr_iter_handlers find_xattr_handlers = {
+static const struct xattr_iter_handlers find_xattr_handlers = {
 	.entry = xattr_entrymatch,
 	.name = xattr_namematch,
 	.alloc_buffer = xattr_checkbuffer,
@@ -291,8 +321,11 @@ static int inline_getxattr(struct inode
 		ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining);
 		if (ret >= 0)
 			break;
+
+		if (ret != -ENOATTR)	/* -ENOMEM, -EIO, etc. */
+			break;
 	}
-	xattr_iter_end(&it->it, true);
+	xattr_iter_end_final(&it->it);
 
 	return ret < 0 ? ret : it->buffer_size;
 }
@@ -315,8 +348,10 @@ static int shared_getxattr(struct inode
 				xattr_iter_end(&it->it, true);
 
 			it->it.page = erofs_get_meta_page(inode->i_sb,
-				blkaddr, false);
-			BUG_ON(IS_ERR(it->it.page));
+							  blkaddr, false);
+			if (IS_ERR(it->it.page))
+				return PTR_ERR(it->it.page);
+
 			it->it.kaddr = kmap_atomic(it->it.page);
 			it->it.blkaddr = blkaddr;
 		}
@@ -324,9 +359,12 @@ static int shared_getxattr(struct inode
 		ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
 		if (ret >= 0)
 			break;
+
+		if (ret != -ENOATTR)	/* -ENOMEM, -EIO, etc. */
+			break;
 	}
 	if (vi->xattr_shared_count)
-		xattr_iter_end(&it->it, true);
+		xattr_iter_end_final(&it->it);
 
 	return ret < 0 ? ret : it->buffer_size;
 }
@@ -351,7 +389,9 @@ int erofs_getxattr(struct inode *inode,
 	if (unlikely(name == NULL))
 		return -EINVAL;
 
-	init_inode_xattrs(inode);
+	ret = init_inode_xattrs(inode);
+	if (ret)
+		return ret;
 
 	it.index = index;
 
@@ -494,7 +534,7 @@ static int xattr_skipvalue(struct xattr_
 	return 1;
 }
 
-static struct xattr_iter_handlers list_xattr_handlers = {
+static const struct xattr_iter_handlers list_xattr_handlers = {
 	.entry = xattr_entrylist,
 	.name = xattr_namelist,
 	.alloc_buffer = xattr_skipvalue,
@@ -516,7 +556,7 @@ static int inline_listxattr(struct listx
 		if (ret < 0)
 			break;
 	}
-	xattr_iter_end(&it->it, true);
+	xattr_iter_end_final(&it->it);
 	return ret < 0 ? ret : it->buffer_ofs;
 }
 
@@ -538,8 +578,10 @@ static int shared_listxattr(struct listx
 				xattr_iter_end(&it->it, true);
 
 			it->it.page = erofs_get_meta_page(inode->i_sb,
-				blkaddr, false);
-			BUG_ON(IS_ERR(it->it.page));
+							  blkaddr, false);
+			if (IS_ERR(it->it.page))
+				return PTR_ERR(it->it.page);
+
 			it->it.kaddr = kmap_atomic(it->it.page);
 			it->it.blkaddr = blkaddr;
 		}
@@ -549,7 +591,7 @@ static int shared_listxattr(struct listx
 			break;
 	}
 	if (vi->xattr_shared_count)
-		xattr_iter_end(&it->it, true);
+		xattr_iter_end_final(&it->it);
 
 	return ret < 0 ? ret : it->buffer_ofs;
 }
@@ -560,7 +602,9 @@ ssize_t erofs_listxattr(struct dentry *d
 	int ret;
 	struct listxattr_iter it;
 
-	init_inode_xattrs(d_inode(dentry));
+	ret = init_inode_xattrs(d_inode(dentry));
+	if (ret)
+		return ret;
 
 	it.dentry = dentry;
 	it.buffer = buffer;


Patches currently in stable-queue which might be from gaoxiang25 at huawei.com are

queue-4.19/staging-erofs-fix-fast-symlink-w-o-xattr-when-fs-xattr-is-on.patch
queue-4.19/staging-erofs-fix-race-of-initializing-xattrs-of-a-inode-at-the-same-time.patch
queue-4.19/staging-erofs-add-error-handling-for-xattr-submodule.patch
queue-4.19/staging-erofs-keep-corrupted-fs-from-crashing-kernel-in-erofs_namei.patch
queue-4.19/staging-erofs-fix-memleak-of-inode-s-shared-xattr-array.patch

Patch "staging: erofs: fix memleak of inode's shared xattr array" has been added to the 4.19-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    staging: erofs: fix memleak of inode's shared xattr array

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     staging-erofs-fix-memleak-of-inode-s-shared-xattr-array.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Tue Mar 12 05:46:41 PDT 2019
From: Gao Xiang <gaoxiang25@huawei.com>
Date: Mon, 11 Mar 2019 14:08:56 +0800
Subject: staging: erofs: fix memleak of inode's shared xattr array
To: <stable at vger.kernel.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>, LKML <linux-kernel at vger.kernel.org>, <linux-erofs at lists.ozlabs.org>, Chao Yu <yuchao0 at huawei.com>, Chao Yu <chao at kernel.org>, Miao Xie <miaoxie at huawei.com>, Fang Wei <fangwei1 at huawei.com>, Sheng Yong <shengyong1 at huawei.com>, Gao Xiang <gaoxiang25 at huawei.com>
Message-ID: <20190311060858.28654-3-gaoxiang25 at huawei.com>

From: Gao Xiang <gaoxiang25@huawei.com>

From: Sheng Yong <shengyong1@huawei.com>

commit 3b1b5291f79d040d549d7c746669fc30e8045b9b upstream.

If it fails to read a shared xattr page, the inode's shared xattr array
is not freed. The next time the inode's xattr is accessed, the previously
allocated array is leaked.

Signed-off-by: Sheng Yong <shengyong1 at huawei.com>
Fixes: b17500a0fdba ("staging: erofs: introduce xattr & acl support")
Cc: <stable at vger.kernel.org> # 4.19+
Reviewed-by: Gao Xiang <gaoxiang25 at huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/staging/erofs/xattr.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -109,8 +109,11 @@ static int init_inode_xattrs(struct inod
 
 			it.page = erofs_get_meta_page(inode->i_sb,
 				++it.blkaddr, S_ISDIR(inode->i_mode));
-			if (IS_ERR(it.page))
+			if (IS_ERR(it.page)) {
+				kfree(vi->xattr_shared_xattrs);
+				vi->xattr_shared_xattrs = NULL;
 				return PTR_ERR(it.page);
+			}
 
 			it.kaddr = kmap_atomic(it.page);
 			atomic_map = true;


Patches currently in stable-queue which might be from gaoxiang25 at huawei.com are

queue-4.19/staging-erofs-fix-fast-symlink-w-o-xattr-when-fs-xattr-is-on.patch
queue-4.19/staging-erofs-fix-race-of-initializing-xattrs-of-a-inode-at-the-same-time.patch
queue-4.19/staging-erofs-add-error-handling-for-xattr-submodule.patch
queue-4.19/staging-erofs-keep-corrupted-fs-from-crashing-kernel-in-erofs_namei.patch
queue-4.19/staging-erofs-fix-memleak-of-inode-s-shared-xattr-array.patch

Patch "staging: erofs: fix race of initializing xattrs of a inode at the same time" has been added to the 4.19-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    staging: erofs: fix race of initializing xattrs of a inode at the same time

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     staging-erofs-fix-race-of-initializing-xattrs-of-a-inode-at-the-same-time.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Tue Mar 12 05:46:41 PDT 2019
From: Gao Xiang <gaoxiang25@huawei.com>
Date: Mon, 11 Mar 2019 14:08:57 +0800
Subject: staging: erofs: fix race of initializing xattrs of a inode at the same time
To: <stable at vger.kernel.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>, LKML <linux-kernel at vger.kernel.org>, <linux-erofs at lists.ozlabs.org>, Chao Yu <yuchao0 at huawei.com>, Chao Yu <chao at kernel.org>, Miao Xie <miaoxie at huawei.com>, Fang Wei <fangwei1 at huawei.com>, Gao Xiang <gaoxiang25 at huawei.com>
Message-ID: <20190311060858.28654-4-gaoxiang25 at huawei.com>

From: Gao Xiang <gaoxiang25@huawei.com>

commit 62dc45979f3f8cb0ea67302a93bff686f0c46c5a upstream.

In real scenario, there could be several threads accessing xattrs
of the same xattr-uninitialized inode, and init_inode_xattrs()
almost at the same time.

That's actually an unexpected behavior, this patch closes the race.

Fixes: b17500a0fdba ("staging: erofs: introduce xattr & acl support")
Cc: <stable at vger.kernel.org> # 4.19+
Reviewed-by: Chao Yu <yuchao0 at huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/staging/erofs/internal.h |   11 +++++++---
 drivers/staging/erofs/xattr.c    |   41 +++++++++++++++++++++++++++------------
 2 files changed, 37 insertions(+), 15 deletions(-)

--- a/drivers/staging/erofs/internal.h
+++ b/drivers/staging/erofs/internal.h
@@ -327,12 +327,17 @@ static inline erofs_off_t iloc(struct er
 	return blknr_to_addr(sbi->meta_blkaddr) + (nid << sbi->islotbits);
 }
 
-#define inode_set_inited_xattr(inode)   (EROFS_V(inode)->flags |= 1)
-#define inode_has_inited_xattr(inode)   (EROFS_V(inode)->flags & 1)
+/* atomic flag definitions */
+#define EROFS_V_EA_INITED_BIT	0
+
+/* bitlock definitions (arranged in reverse order) */
+#define EROFS_V_BL_XATTR_BIT	(BITS_PER_LONG - 1)
 
 struct erofs_vnode {
 	erofs_nid_t nid;
-	unsigned int flags;
+
+	/* atomic flags (including bitlocks) */
+	unsigned long flags;
 
 	unsigned char data_mapping_mode;
 	/* inline size in bytes */
--- a/drivers/staging/erofs/xattr.c
+++ b/drivers/staging/erofs/xattr.c
@@ -44,17 +44,24 @@ static inline void xattr_iter_end_final(
 
 static int init_inode_xattrs(struct inode *inode)
 {
+	struct erofs_vnode *const vi = EROFS_V(inode);
 	struct xattr_iter it;
 	unsigned i;
 	struct erofs_xattr_ibody_header *ih;
 	struct erofs_sb_info *sbi;
-	struct erofs_vnode *vi;
 	bool atomic_map;
+	int ret = 0;
 
-	if (likely(inode_has_inited_xattr(inode)))
+	/* the most case is that xattrs of this inode are initialized. */
+	if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags))
 		return 0;
 
-	vi = EROFS_V(inode);
+	if (wait_on_bit_lock(&vi->flags, EROFS_V_BL_XATTR_BIT, TASK_KILLABLE))
+		return -ERESTARTSYS;
+
+	/* someone has initialized xattrs for us? */
+	if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags))
+		goto out_unlock;
 
 	/*
 	 * bypass all xattr operations if ->xattr_isize is not greater than
@@ -67,13 +74,16 @@ static int init_inode_xattrs(struct inod
 	if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) {
 		errln("xattr_isize %d of nid %llu is not supported yet",
 		      vi->xattr_isize, vi->nid);
-		return -ENOTSUPP;
+		ret = -ENOTSUPP;
+		goto out_unlock;
 	} else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {
 		if (unlikely(vi->xattr_isize)) {
 			DBG_BUGON(1);
-			return -EIO;	/* xattr ondisk layout error */
+			ret = -EIO;
+			goto out_unlock;	/* xattr ondisk layout error */
 		}
-		return -ENOATTR;
+		ret = -ENOATTR;
+		goto out_unlock;
 	}
 
 	sbi = EROFS_I_SB(inode);
@@ -81,8 +91,10 @@ static int init_inode_xattrs(struct inod
 	it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);
 
 	it.page = erofs_get_inline_page(inode, it.blkaddr);
-	if (IS_ERR(it.page))
-		return PTR_ERR(it.page);
+	if (IS_ERR(it.page)) {
+		ret = PTR_ERR(it.page);
+		goto out_unlock;
+	}
 
 	/* read in shared xattr array (non-atomic, see kmalloc below) */
 	it.kaddr = kmap(it.page);
@@ -95,7 +107,8 @@ static int init_inode_xattrs(struct inod
 						sizeof(uint), GFP_KERNEL);
 	if (!vi->xattr_shared_xattrs) {
 		xattr_iter_end(&it, atomic_map);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto out_unlock;
 	}
 
 	/* let's skip ibody header */
@@ -112,7 +125,8 @@ static int init_inode_xattrs(struct inod
 			if (IS_ERR(it.page)) {
 				kfree(vi->xattr_shared_xattrs);
 				vi->xattr_shared_xattrs = NULL;
-				return PTR_ERR(it.page);
+				ret = PTR_ERR(it.page);
+				goto out_unlock;
 			}
 
 			it.kaddr = kmap_atomic(it.page);
@@ -125,8 +139,11 @@ static int init_inode_xattrs(struct inod
 	}
 	xattr_iter_end(&it, atomic_map);
 
-	inode_set_inited_xattr(inode);
-	return 0;
+	set_bit(EROFS_V_EA_INITED_BIT, &vi->flags);
+
+out_unlock:
+	clear_and_wake_up_bit(EROFS_V_BL_XATTR_BIT, &vi->flags);
+	return ret;
 }
 
 struct xattr_iter_handlers {


Patches currently in stable-queue which might be from gaoxiang25 at huawei.com are

queue-4.19/staging-erofs-fix-fast-symlink-w-o-xattr-when-fs-xattr-is-on.patch
queue-4.19/staging-erofs-fix-race-of-initializing-xattrs-of-a-inode-at-the-same-time.patch
queue-4.19/staging-erofs-add-error-handling-for-xattr-submodule.patch
queue-4.19/staging-erofs-keep-corrupted-fs-from-crashing-kernel-in-erofs_namei.patch
queue-4.19/staging-erofs-fix-memleak-of-inode-s-shared-xattr-array.patch

Patch "staging: erofs: keep corrupted fs from crashing kernel in erofs_namei()" has been added to the 4.19-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    staging: erofs: keep corrupted fs from crashing kernel in erofs_namei()

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     staging-erofs-keep-corrupted-fs-from-crashing-kernel-in-erofs_namei.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Tue Mar 12 05:46:41 PDT 2019
From: Gao Xiang <gaoxiang25@huawei.com>
Date: Mon, 11 Mar 2019 14:08:58 +0800
Subject: staging: erofs: keep corrupted fs from crashing kernel in erofs_namei()
To: <stable at vger.kernel.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>, LKML <linux-kernel at vger.kernel.org>, <linux-erofs at lists.ozlabs.org>, Chao Yu <yuchao0 at huawei.com>, Chao Yu <chao at kernel.org>, Miao Xie <miaoxie at huawei.com>, Fang Wei <fangwei1 at huawei.com>, Gao Xiang <gaoxiang25 at huawei.com>
Message-ID: <20190311060858.28654-5-gaoxiang25 at huawei.com>

From: Gao Xiang <gaoxiang25@huawei.com>

commit 419d6efc50e94bcf5d6b35cd8c71f79edadec564 upstream.

As Al pointed out, "
... and while we are at it, what happens to
	unsigned int nameoff = le16_to_cpu(de[mid].nameoff);
	unsigned int matched = min(startprfx, endprfx);

	struct qstr dname = QSTR_INIT(data + nameoff,
		unlikely(mid >= ndirents - 1) ?
			maxsize - nameoff :
			le16_to_cpu(de[mid + 1].nameoff) - nameoff);

	/* string comparison without already matched prefix */
	int ret = dirnamecmp(name, &dname, &matched);
if le16_to_cpu(de[...].nameoff) is not monotonically increasing?  I.e.
what's to prevent e.g. (unsigned)-1 ending up in dname.len?

Corrupted fs image shouldn't oops the kernel.. "

Revisit the related lookup flow to address the issue.

Fixes: d72d1ce60174 ("staging: erofs: add namei functions")
Cc: <stable at vger.kernel.org> # 4.19+
Suggested-by: Al Viro <viro at ZenIV.linux.org.uk>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/staging/erofs/namei.c |  189 ++++++++++++++++++++++--------------------
 1 file changed, 100 insertions(+), 89 deletions(-)

--- a/drivers/staging/erofs/namei.c
+++ b/drivers/staging/erofs/namei.c
@@ -15,74 +15,77 @@
 
 #include <trace/events/erofs.h>
 
-/* based on the value of qn->len is accurate */
-static inline int dirnamecmp(struct qstr *qn,
-	struct qstr *qd, unsigned *matched)
+struct erofs_qstr {
+	const unsigned char *name;
+	const unsigned char *end;
+};
+
+/* based on the end of qn is accurate and it must have the trailing '\0' */
+static inline int dirnamecmp(const struct erofs_qstr *qn,
+			     const struct erofs_qstr *qd,
+			     unsigned int *matched)
 {
-	unsigned i = *matched, len = min(qn->len, qd->len);
-loop:
-	if (unlikely(i >= len)) {
-		*matched = i;
-		if (qn->len < qd->len) {
-			/*
-			 * actually (qn->len == qd->len)
-			 * when qd->name[i] == '\0'
-			 */
-			return qd->name[i] == '\0' ? 0 : -1;
-		}
-		return (qn->len > qd->len);
-	}
+	unsigned int i = *matched;
 
-	if (qn->name[i] != qd->name[i]) {
-		*matched = i;
-		return qn->name[i] > qd->name[i] ? 1 : -1;
+	/*
+	 * on-disk error, let's only BUG_ON in the debugging mode.
+	 * otherwise, it will return 1 to just skip the invalid name
+	 * and go on (in consideration of the lookup performance).
+	 */
+	DBG_BUGON(qd->name > qd->end);
+
+	/* qd could not have trailing '\0' */
+	/* However it is absolutely safe if < qd->end */
+	while (qd->name + i < qd->end && qd->name[i] != '\0') {
+		if (qn->name[i] != qd->name[i]) {
+			*matched = i;
+			return qn->name[i] > qd->name[i] ? 1 : -1;
+		}
+		++i;
 	}
-
-	++i;
-	goto loop;
+	*matched = i;
+	/* See comments in __d_alloc on the terminating NUL character */
+	return qn->name[i] == '\0' ? 0 : 1;
 }
 
-static struct erofs_dirent *find_target_dirent(
-	struct qstr *name,
-	u8 *data, int maxsize)
+#define nameoff_from_disk(off, sz)	(le16_to_cpu(off) & ((sz) - 1))
+
+static struct erofs_dirent *find_target_dirent(struct erofs_qstr *name,
+					       u8 *data,
+					       unsigned int dirblksize,
+					       const int ndirents)
 {
-	unsigned ndirents, head, back;
-	unsigned startprfx, endprfx;
+	int head, back;
+	unsigned int startprfx, endprfx;
 	struct erofs_dirent *const de = (struct erofs_dirent *)data;
 
-	/* make sure that maxsize is valid */
-	BUG_ON(maxsize < sizeof(struct erofs_dirent));
-
-	ndirents = le16_to_cpu(de->nameoff) / sizeof(*de);
-
-	/* corrupted dir (may be unnecessary...) */
-	BUG_ON(!ndirents);
-
-	head = 0;
+	/* since the 1st dirent has been evaluated previously */
+	head = 1;
 	back = ndirents - 1;
 	startprfx = endprfx = 0;
 
 	while (head <= back) {
-		unsigned mid = head + (back - head) / 2;
-		unsigned nameoff = le16_to_cpu(de[mid].nameoff);
-		unsigned matched = min(startprfx, endprfx);
-
-		struct qstr dname = QSTR_INIT(data + nameoff,
-			unlikely(mid >= ndirents - 1) ?
-				maxsize - nameoff :
-				le16_to_cpu(de[mid + 1].nameoff) - nameoff);
+		const int mid = head + (back - head) / 2;
+		const int nameoff = nameoff_from_disk(de[mid].nameoff,
+						      dirblksize);
+		unsigned int matched = min(startprfx, endprfx);
+		struct erofs_qstr dname = {
+			.name = data + nameoff,
+			.end = unlikely(mid >= ndirents - 1) ?
+				data + dirblksize :
+				data + nameoff_from_disk(de[mid + 1].nameoff,
+							 dirblksize)
+		};
 
 		/* string comparison without already matched prefix */
 		int ret = dirnamecmp(name, &dname, &matched);
 
-		if (unlikely(!ret))
+		if (unlikely(!ret)) {
 			return de + mid;
-		else if (ret > 0) {
+		} else if (ret > 0) {
 			head = mid + 1;
 			startprfx = matched;
-		} else if (unlikely(mid < 1))	/* fix "mid" overflow */
-			break;
-		else {
+		} else {
 			back = mid - 1;
 			endprfx = matched;
 		}
@@ -91,12 +94,12 @@ static struct erofs_dirent *find_target_
 	return ERR_PTR(-ENOENT);
 }
 
-static struct page *find_target_block_classic(
-	struct inode *dir,
-	struct qstr *name, int *_diff)
+static struct page *find_target_block_classic(struct inode *dir,
+					      struct erofs_qstr *name,
+					      int *_ndirents)
 {
-	unsigned startprfx, endprfx;
-	unsigned head, back;
+	unsigned int startprfx, endprfx;
+	int head, back;
 	struct address_space *const mapping = dir->i_mapping;
 	struct page *candidate = ERR_PTR(-ENOENT);
 
@@ -105,41 +108,43 @@ static struct page *find_target_block_cl
 	back = inode_datablocks(dir) - 1;
 
 	while (head <= back) {
-		unsigned mid = head + (back - head) / 2;
+		const int mid = head + (back - head) / 2;
 		struct page *page = read_mapping_page(mapping, mid, NULL);
 
-		if (IS_ERR(page)) {
-exact_out:
-			if (!IS_ERR(candidate)) /* valid candidate */
-				put_page(candidate);
-			return page;
-		} else {
-			int diff;
-			unsigned ndirents, matched;
-			struct qstr dname;
+		if (!IS_ERR(page)) {
 			struct erofs_dirent *de = kmap_atomic(page);
-			unsigned nameoff = le16_to_cpu(de->nameoff);
-
-			ndirents = nameoff / sizeof(*de);
+			const int nameoff = nameoff_from_disk(de->nameoff,
+							      EROFS_BLKSIZ);
+			const int ndirents = nameoff / sizeof(*de);
+			int diff;
+			unsigned int matched;
+			struct erofs_qstr dname;
 
-			/* corrupted dir (should have one entry at least) */
-			BUG_ON(!ndirents || nameoff > PAGE_SIZE);
+			if (unlikely(!ndirents)) {
+				DBG_BUGON(1);
+				kunmap_atomic(de);
+				put_page(page);
+				page = ERR_PTR(-EIO);
+				goto out;
+			}
 
 			matched = min(startprfx, endprfx);
 
 			dname.name = (u8 *)de + nameoff;
-			dname.len = ndirents == 1 ?
-				/* since the rest of the last page is 0 */
-				EROFS_BLKSIZ - nameoff
-				: le16_to_cpu(de[1].nameoff) - nameoff;
+			if (ndirents == 1)
+				dname.end = (u8 *)de + EROFS_BLKSIZ;
+			else
+				dname.end = (u8 *)de +
+					nameoff_from_disk(de[1].nameoff,
+							  EROFS_BLKSIZ);
 
 			/* string comparison without already matched prefix */
 			diff = dirnamecmp(name, &dname, &matched);
 			kunmap_atomic(de);
 
 			if (unlikely(!diff)) {
-				*_diff = 0;
-				goto exact_out;
+				*_ndirents = 0;
+				goto out;
 			} else if (diff > 0) {
 				head = mid + 1;
 				startprfx = matched;
@@ -147,45 +152,51 @@ exact_out:
 				if (likely(!IS_ERR(candidate)))
 					put_page(candidate);
 				candidate = page;
+				*_ndirents = ndirents;
 			} else {
 				put_page(page);
 
-				if (unlikely(mid < 1))	/* fix "mid" overflow */
-					break;
-
 				back = mid - 1;
 				endprfx = matched;
 			}
+			continue;
 		}
+out:		/* free if the candidate is valid */
+		if (!IS_ERR(candidate))
+			put_page(candidate);
+		return page;
 	}
-	*_diff = 1;
 	return candidate;
 }
 
 int erofs_namei(struct inode *dir,
-	struct qstr *name,
-	erofs_nid_t *nid, unsigned *d_type)
+		struct qstr *name,
+		erofs_nid_t *nid, unsigned int *d_type)
 {
-	int diff;
+	int ndirents;
 	struct page *page;
-	u8 *data;
+	void *data;
 	struct erofs_dirent *de;
+	struct erofs_qstr qn;
 
 	if (unlikely(!dir->i_size))
 		return -ENOENT;
 
-	diff = 1;
-	page = find_target_block_classic(dir, name, &diff);
+	qn.name = name->name;
+	qn.end = name->name + name->len;
+
+	ndirents = 0;
+	page = find_target_block_classic(dir, &qn, &ndirents);
 
 	if (unlikely(IS_ERR(page)))
 		return PTR_ERR(page);
 
 	data = kmap_atomic(page);
 	/* the target page has been mapped */
-	de = likely(diff) ?
-		/* since the rest of the last page is 0 */
-		find_target_dirent(name, data, EROFS_BLKSIZ) :
-		(struct erofs_dirent *)data;
+	if (ndirents)
+		de = find_target_dirent(&qn, data, EROFS_BLKSIZ, ndirents);
+	else
+		de = (struct erofs_dirent *)data;
 
 	if (likely(!IS_ERR(de))) {
 		*nid = le64_to_cpu(de->nid);


Patches currently in stable-queue which might be from gaoxiang25 at huawei.com are

queue-4.19/staging-erofs-fix-fast-symlink-w-o-xattr-when-fs-xattr-is-on.patch
queue-4.19/staging-erofs-fix-race-of-initializing-xattrs-of-a-inode-at-the-same-time.patch
queue-4.19/staging-erofs-add-error-handling-for-xattr-submodule.patch
queue-4.19/staging-erofs-keep-corrupted-fs-from-crashing-kernel-in-erofs_namei.patch
queue-4.19/staging-erofs-fix-memleak-of-inode-s-shared-xattr-array.patch