ocfs2_validate_dx_leaf() and ocfs2_validate_dx_root() check the ECC and
signature of an indexed-directory block before it reaches higher-level
callers, but neither validator bounds the ocfs2_dx_entry_list counts
against the capacity of the block that holds them.
ocfs2_dx_dir_search() then walks
for (i = 0; i < le16_to_cpu(entry_list->de_num_used); i++)
dx_entry = &entry_list->de_entries[i];
over de_num_used entries with no bounds check. entry_list is either
dx_leaf->dl_list (from ocfs2_read_dx_leaf) or, for an inline root,
dx_root->dr_entries. A crafted on-disk image can set de_num_used (and
de_count, which is the __counted_by_le() bound of de_entries) to 0xffff
and make the walk read far past the end of the 4KB metadata block, giving
a slab out-of-bounds read reachable from any path lookup, stat() or open()
on an indexed directory once the image is mounted.
Commit 775c17386a6f ("ocfs2: validate dx_root extent list fields during
block read") already bounds dr_list for the non-inline dx_root, but left
the inline dr_entries path and the dx_leaf dl_list unchecked. Add the
same read-time validation for both entry lists: de_count must equal the
capacity of the block (ocfs2_dx_entries_per_leaf()/per_root()) and
de_num_used must not exceed de_count, rejecting corrupted metadata with
-EFSCORRUPTED before ocfs2_dx_dir_search() can walk an out-of-range entry
array.
de_count is always written as exactly the block capacity when a leaf or
inline root is formatted, so the equality check does not reject any
valid image.
Fixes: 9b7895efac90 ("ocfs2: Add a name indexed b-tree to directory inodes")
Fixes: 4ed8a6bb083b ("ocfs2: Store dir index records inline")
Cc: [email protected]
Found by 0sec automated security-research tooling (https://0sec.ai).
Assisted-by: 0sec:claude-opus-4-8
Signed-off-by: Doruk Tan Ozturk <[email protected]>
---
fs/ocfs2/dir.c | 45 +++++++++++++++++++++++++++++++++++++++++----
1 file changed, 41 insertions(+), 4 deletions(-)
diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index baf3eca7b4e4..fcc3721cbe34 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -624,6 +624,28 @@ static int ocfs2_validate_dx_root(struct super_block *sb,
le16_to_cpu(el->l_count));
goto bail;
}
+ } else {
+ struct ocfs2_dx_entry_list *dl_list = &dx_root->dr_entries;
+
+ if (le16_to_cpu(dl_list->de_count) !=
+ ocfs2_dx_entries_per_root(sb)) {
+ ret = ocfs2_error(sb,
+ "Dir Index Root # %llu has invalid
de_count %u (expected %u)\n",
+ (unsigned long
long)le64_to_cpu(dx_root->dr_blkno),
+ le16_to_cpu(dl_list->de_count),
+ ocfs2_dx_entries_per_root(sb));
+ goto bail;
+ }
+
+ if (le16_to_cpu(dl_list->de_num_used) >
+ le16_to_cpu(dl_list->de_count)) {
+ ret = ocfs2_error(sb,
+ "Dir Index Root # %llu has invalid
de_num_used %u (de_count %u)\n",
+ (unsigned long
long)le64_to_cpu(dx_root->dr_blkno),
+ le16_to_cpu(dl_list->de_num_used),
+ le16_to_cpu(dl_list->de_count));
+ goto bail;
+ }
}
bail:
@@ -663,10 +685,25 @@ static int ocfs2_validate_dx_leaf(struct super_block *sb,
return ret;
}
- if (!OCFS2_IS_VALID_DX_LEAF(dx_leaf)) {
- ret = ocfs2_error(sb, "Dir Index Leaf has bad signature %.*s\n",
- 7, dx_leaf->dl_signature);
- }
+ if (!OCFS2_IS_VALID_DX_LEAF(dx_leaf))
+ return ocfs2_error(sb, "Dir Index Leaf has bad signature
%.*s\n",
+ 7, dx_leaf->dl_signature);
+
+ if (le16_to_cpu(dx_leaf->dl_list.de_count) !=
+ ocfs2_dx_entries_per_leaf(sb))
+ return ocfs2_error(sb,
+ "Dir Index Leaf # %llu has invalid de_count
%u (expected %u)\n",
+ (unsigned long
long)le64_to_cpu(dx_leaf->dl_blkno),
+ le16_to_cpu(dx_leaf->dl_list.de_count),
+ ocfs2_dx_entries_per_leaf(sb));
+
+ if (le16_to_cpu(dx_leaf->dl_list.de_num_used) >
+ le16_to_cpu(dx_leaf->dl_list.de_count))
+ return ocfs2_error(sb,
+ "Dir Index Leaf # %llu has invalid
de_num_used %u (de_count %u)\n",
+ (unsigned long
long)le64_to_cpu(dx_leaf->dl_blkno),
+ le16_to_cpu(dx_leaf->dl_list.de_num_used),
+ le16_to_cpu(dx_leaf->dl_list.de_count));
return ret;
}
--
2.43.0
