FAILED: patch "[PATCH] ocfs2: fix array out of bound access in __ocfs2_find_path()" failed to apply to 6.18-stable tree

FAILED: patch "[PATCH] ocfs2: fix array out of bound access in __ocfs2_find_path()" failed to apply to 6.18-stable tree

[Sasha Levin]

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 6193ce7896afb52a321a0063c8b6a45e477a84e2
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107051119-failed-6.18-6193ce7896af@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 6193ce7896afb52a321a0063c8b6a45e477a84e2 Mon Sep 17 00:00:00 2001
From: Giorgi Kobakhia <gkobakhi@asu.edu>
Date: Tue, 22 Sep 2026 13:21:59 -0700
Subject: [PATCH] ocfs2: fix array out of bound access in __ocfs2_find_path()

__ocfs2_find_path() walks down the extent tree and records path by calling
find_path_ins(), which appends entry to path->p_node[].  It only has 5
spots.

A corrupted ocfs2 image whose extent block is pointing to itself causes
__ocfs2_find_path() descent endlessly, writing past the end of
path->p_node[] array.

 UBSAN: array-index-out-of-bounds in fs/ocfs2/alloc.c:677:14
 index 5 is out of range for type 'ocfs2_path_item [5]'
 Call Trace:
  <TASK>
  find_path_ins (fs/ocfs2/alloc.c:677 fs/ocfs2/alloc.c:1914)
  __ocfs2_find_path.constprop.0 (fs/ocfs2/alloc.c:1882)
  ocfs2_commit_truncate (fs/ocfs2/alloc.c:1924 fs/ocfs2/alloc.c:7286)
  ocfs2_truncate_file (fs/ocfs2/file.c:515)
  ocfs2_setattr (fs/ocfs2/file.c:1224)
  notify_change (fs/attr.c:556)
  do_truncate (fs/open.c:68)
  do_ftruncate (fs/open.c:194 (discriminator 1))
  ksys_ftruncate (fs/open.c:206)
  __x64_sys_ftruncate (fs/open.c:211 fs/open.c:209 fs/open.c:209)

Commit a406aff8c051 ("ocfs2: validate l_tree_depth to avoid out-of-bounds
access") already restricts el->l_tree_depth to be less than
OCFS2_MAX_PATH_DEPTH, which is equal to 5.  However, does not handle the
infinite descent case.

Check if the el->l_tree_depth decreases on each descent.  Maximum descents
are restricted to 4 and the path->p_node[] array does not overflow.

Link: https://lore.kernel.org/20260922202159.2421642-1-gkobakhi@asu.edu
Fixes: dcd0538ff4e8 ("ocfs2: sparse b-tree support")
Signed-off-by: Giorgi Kobakhia <gkobakhi@asu.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Xiang Mei <xmei5@asu.edu>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Assisted-by: LLM
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: <stable@vger.kernel.org>
---
 fs/ocfs2/alloc.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index 2fdc5403b10b0..fc949e5946269 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -1844,6 +1844,7 @@ static int __ocfs2_find_path(struct ocfs2_caching_info *ci,
 	int i, ret = 0;
 	u32 range;
 	u64 blkno;
+	u32 prev_depth = OCFS2_MAX_PATH_DEPTH;
 	struct buffer_head *bh = NULL;
 	struct ocfs2_extent_block *eb;
 	struct ocfs2_extent_list *el;
@@ -1851,14 +1852,16 @@ static int __ocfs2_find_path(struct ocfs2_caching_info *ci,
 
 	el = root_el;
 	while (el->l_tree_depth) {
-		if (unlikely(le16_to_cpu(el->l_tree_depth) >= OCFS2_MAX_PATH_DEPTH)) {
+		if (unlikely(le16_to_cpu(el->l_tree_depth) >= prev_depth)) {
 			ocfs2_error(ocfs2_metadata_cache_get_super(ci),
-				    "Owner %llu has invalid tree depth %u in extent list\n",
+				    "Owner %llu has invalid tree depth %u in extent list (max %u)\n",
 				    (unsigned long long)ocfs2_metadata_cache_owner(ci),
-				    le16_to_cpu(el->l_tree_depth));
+				    le16_to_cpu(el->l_tree_depth), prev_depth - 1);
 			ret = -EROFS;
 			goto out;
 		}
+		prev_depth = le16_to_cpu(el->l_tree_depth);
+
 		if (!el->l_next_free_rec || !el->l_count) {
 			ocfs2_error(ocfs2_metadata_cache_get_super(ci),
 				    "Owner %llu has empty extent list at depth %u\n"
-- 
2.53.0

[PATCH 6.18.y 1/2] ocfs2: fix oob in __ocfs2_find_path

[Sasha Levin]

From: Edward Adam Davis <eadavis@qq.com>

[ Upstream commit e0b0f2834c9bec51b1068de5cf5e10c7519143eb ]

syzbot constructed a corrupted image, which resulted in el->l_count from
the b-tree extent block being 0.  Since the length of the l_recs array
depends on l_count, reading its member e_blkno triggered the out-of-bounds
access reported by syzbot in [1].

The loop terminates when l_count is 0, similar to when next_free is 0.

[1]
UBSAN: array-index-out-of-bounds in fs/ocfs2/alloc.c:1838:11
index 0 is out of range for type 'struct ocfs2_extent_rec[] __counted_by(l_count)' (aka 'struct ocfs2_extent_rec[]')
Call Trace:
 __ocfs2_find_path+0x606/0xa40 fs/ocfs2/alloc.c:1838
 ocfs2_find_leaf+0xab/0x1c0 fs/ocfs2/alloc.c:1946
 ocfs2_get_clusters_nocache+0x172/0xc60 fs/ocfs2/extent_map.c:418
 ocfs2_get_clusters+0x505/0xa70 fs/ocfs2/extent_map.c:631
 ocfs2_extent_map_get_blocks+0x202/0x6a0 fs/ocfs2/extent_map.c:678
 ocfs2_read_virt_blocks+0x286/0x930 fs/ocfs2/extent_map.c:1001
 ocfs2_read_dir_block fs/ocfs2/dir.c:521 [inline]
 ocfs2_find_entry_el fs/ocfs2/dir.c:728 [inline]
 ocfs2_find_entry+0x3e4/0x2090 fs/ocfs2/dir.c:1120
 ocfs2_find_files_on_disk+0xdf/0x310 fs/ocfs2/dir.c:2023
 ocfs2_lookup_ino_from_name+0x52/0x100 fs/ocfs2/dir.c:2045
 _ocfs2_get_system_file_inode fs/ocfs2/sysfile.c:136 [inline]
 ocfs2_get_system_file_inode+0x326/0x770 fs/ocfs2/sysfile.c:112
 ocfs2_init_global_system_inodes+0x319/0x660 fs/ocfs2/super.c:461
 ocfs2_initialize_super fs/ocfs2/super.c:2196 [inline]
 ocfs2_fill_super+0x4432/0x65b0 fs/ocfs2/super.c:993
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1691
 vfs_get_tree+0x92/0x2a0 fs/super.c:1751
 fc_mount fs/namespace.c:1199 [inline]

Link: https://lkml.kernel.org/r/tencent_4D99464FA28D9225BE0DBA923F5DF6DD8C07@qq.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Reported-by: syzbot+151afab124dfbc5f15e6@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=151afab124dfbc5f15e6
Reviewed-by: Heming Zhao <heming.zhao@suse.com>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 6193ce7896af ("ocfs2: fix array out of bound access in __ocfs2_find_path()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ocfs2/alloc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index fb7d8dc2129be..d35c6761dd124 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -1811,14 +1811,15 @@ static int __ocfs2_find_path(struct ocfs2_caching_info *ci,
 			ret = -EROFS;
 			goto out;
 		}
-		if (le16_to_cpu(el->l_next_free_rec) == 0) {
+		if (!el->l_next_free_rec || !el->l_count) {
 			ocfs2_error(ocfs2_metadata_cache_get_super(ci),
-				    "Owner %llu has empty extent list at depth %u\n",
+				    "Owner %llu has empty extent list at depth %u\n"
+				    "(next free=%u count=%u)\n",
 				    (unsigned long long)ocfs2_metadata_cache_owner(ci),
-				    le16_to_cpu(el->l_tree_depth));
+				    le16_to_cpu(el->l_tree_depth),
+				    le16_to_cpu(el->l_next_free_rec), le16_to_cpu(el->l_count));
 			ret = -EROFS;
 			goto out;
-
 		}
 
 		for(i = 0; i < le16_to_cpu(el->l_next_free_rec) - 1; i++) {
-- 
2.53.0

[PATCH 6.18.y 2/2] ocfs2: fix array out of bound access in __ocfs2_find_path()

[Sasha Levin]

From: Giorgi Kobakhia <gkobakhi@asu.edu>

[ Upstream commit 6193ce7896afb52a321a0063c8b6a45e477a84e2 ]

__ocfs2_find_path() walks down the extent tree and records path by calling
find_path_ins(), which appends entry to path->p_node[].  It only has 5
spots.

A corrupted ocfs2 image whose extent block is pointing to itself causes
__ocfs2_find_path() descent endlessly, writing past the end of
path->p_node[] array.

 UBSAN: array-index-out-of-bounds in fs/ocfs2/alloc.c:677:14
 index 5 is out of range for type 'ocfs2_path_item [5]'
 Call Trace:
  <TASK>
  find_path_ins (fs/ocfs2/alloc.c:677 fs/ocfs2/alloc.c:1914)
  __ocfs2_find_path.constprop.0 (fs/ocfs2/alloc.c:1882)
  ocfs2_commit_truncate (fs/ocfs2/alloc.c:1924 fs/ocfs2/alloc.c:7286)
  ocfs2_truncate_file (fs/ocfs2/file.c:515)
  ocfs2_setattr (fs/ocfs2/file.c:1224)
  notify_change (fs/attr.c:556)
  do_truncate (fs/open.c:68)
  do_ftruncate (fs/open.c:194 (discriminator 1))
  ksys_ftruncate (fs/open.c:206)
  __x64_sys_ftruncate (fs/open.c:211 fs/open.c:209 fs/open.c:209)

Commit a406aff8c051 ("ocfs2: validate l_tree_depth to avoid out-of-bounds
access") already restricts el->l_tree_depth to be less than
OCFS2_MAX_PATH_DEPTH, which is equal to 5.  However, does not handle the
infinite descent case.

Check if the el->l_tree_depth decreases on each descent.  Maximum descents
are restricted to 4 and the path->p_node[] array does not overflow.

Link: https://lore.kernel.org/20260922202159.2421642-1-gkobakhi@asu.edu
Fixes: dcd0538ff4e8 ("ocfs2: sparse b-tree support")
Signed-off-by: Giorgi Kobakhia <gkobakhi@asu.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Xiang Mei <xmei5@asu.edu>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Assisted-by: LLM
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ocfs2/alloc.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index d35c6761dd124..27b8832d7820a 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -1796,6 +1796,7 @@ static int __ocfs2_find_path(struct ocfs2_caching_info *ci,
 	int i, ret = 0;
 	u32 range;
 	u64 blkno;
+	u32 prev_depth = OCFS2_MAX_PATH_DEPTH;
 	struct buffer_head *bh = NULL;
 	struct ocfs2_extent_block *eb;
 	struct ocfs2_extent_list *el;
@@ -1803,14 +1804,16 @@ static int __ocfs2_find_path(struct ocfs2_caching_info *ci,
 
 	el = root_el;
 	while (el->l_tree_depth) {
-		if (unlikely(le16_to_cpu(el->l_tree_depth) >= OCFS2_MAX_PATH_DEPTH)) {
+		if (unlikely(le16_to_cpu(el->l_tree_depth) >= prev_depth)) {
 			ocfs2_error(ocfs2_metadata_cache_get_super(ci),
-				    "Owner %llu has invalid tree depth %u in extent list\n",
+				    "Owner %llu has invalid tree depth %u in extent list (max %u)\n",
 				    (unsigned long long)ocfs2_metadata_cache_owner(ci),
-				    le16_to_cpu(el->l_tree_depth));
+				    le16_to_cpu(el->l_tree_depth), prev_depth - 1);
 			ret = -EROFS;
 			goto out;
 		}
+		prev_depth = le16_to_cpu(el->l_tree_depth);
+
 		if (!el->l_next_free_rec || !el->l_count) {
 			ocfs2_error(ocfs2_metadata_cache_get_super(ci),
 				    "Owner %llu has empty extent list at depth %u\n"
-- 
2.53.0