[PATCH v3] ocfs2: validate l_tree_depth to avoid out-of-bounds access

From: Vasiliy Kovalev
Date: Fri Feb 14 2025 - 03:49:34 EST


The l_tree_depth field is 16-bit (__le16), but the actual
maximum depth is limited to OCFS2_MAX_PATH_DEPTH.

Add a check to prevent out-of-bounds access if l_tree_depth
has an invalid value, which may occur when reading from a
corrupted mounted disk [1].

Fixes: ccd979bdbce9 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem")
Reported-by: syzbot+66c146268dc88f4341fd@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=66c146268dc88f4341fd [1]
Signed-off-by: Vasiliy Kovalev <kovalev@xxxxxxxxxxxx>
---
v3: Change the condition "> OCFS2_MAX_PATH_DEPTH" to ">= OCFS2_MAX_PATH_DEPTH"
v2: Restricted depth to OCFS2_MAX_PATH_DEPTH and moved the check
to __ocfs2_find_path().
---
fs/ocfs2/alloc.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index 4414743b638e8..cec8fc5cb8e87 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -1803,6 +1803,14 @@ 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)) {
+ ocfs2_error(ocfs2_metadata_cache_get_super(ci),
+ "Owner %llu has invalid tree depth %u in extent list\n",
+ (unsigned long long)ocfs2_metadata_cache_owner(ci),
+ le16_to_cpu(el->l_tree_depth));
+ ret = -EROFS;
+ goto out;
+ }
if (le16_to_cpu(el->l_next_free_rec) == 0) {
ocfs2_error(ocfs2_metadata_cache_get_super(ci),
"Owner %llu has empty extent list at depth %u\n",
--
2.42.2