+ ocfs2-validate-directory-index-entry-counts-when-reading-metadata.patch added to mm-nonmm-unstable branch

The patch titled
     Subject: ocfs2: validate directory-index entry counts when reading metadata
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     ocfs2-validate-directory-index-entry-counts-when-reading-metadata.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ocfs2-validate-directory-index-entry-counts-when-reading-metadata.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Doruk Tan Ozturk <[email protected]>
Subject: ocfs2: validate directory-index entry counts when reading metadata
Date: Mon, 13 Jul 2026 22:56:25 +0200

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.

Found by 0sec automated security-research tooling (https://0sec.ai).

Link: https://lore.kernel.org/[email protected]
Fixes: 9b7895efac90 ("ocfs2: Add a name indexed b-tree to directory inodes")
Fixes: 4ed8a6bb083b ("ocfs2: Store dir index records inline")
Assisted-by: 0sec:claude-opus-4-8
Signed-off-by: Doruk Tan Ozturk <[email protected]>
Reviewed-by: Joseph Qi <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Junxiao Bi <[email protected]>
Cc: Changwei Ge <[email protected]>
Cc: Jun Piao <[email protected]>
Cc: Heming Zhao <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 fs/ocfs2/dir.c |   45 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 4 deletions(-)

--- a/fs/ocfs2/dir.c~ocfs2-validate-directory-index-entry-counts-when-reading-metadata
+++ a/fs/ocfs2/dir.c
@@ -625,6 +625,28 @@ static int ocfs2_validate_dx_root(struct
 					  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:
@@ -664,10 +686,25 @@ static int ocfs2_validate_dx_leaf(struct
 		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;
 }
_

Patches currently in -mm which might be from [email protected] are

ocfs2-validate-directory-index-entry-counts-when-reading-metadata.patch