In the Linux kernel, the following vulnerability has been resolved:

f2fs: invalidate dentry cache on failed whiteout creation

F2FS can mount filesystems with corrupted directory depth values that
get runtime-clamped to MAX_DIR_HASH_DEPTH. When RENAME_WHITEOUT
operations are performed on such directories, f2fs_rename performs
directory modifications (updating target entry and deleting source
entry) before attempting to add the whiteout entry via f2fs_add_link.

If f2fs_add_link fails due to the corrupted directory structure, the
function returns an error to VFS, but the partial directory
modifications have already been committed to disk. VFS assumes the
entire rename operation failed and does not update the dentry cache,
leaving stale mappings.

In the error path, VFS does not call d_move() to update the dentry
cache. This results in new_dentry still pointing to the old inode
(new_inode) which has already had its i_nlink decremented to zero.
The stale cache causes subsequent operations to incorrectly reference
the freed inode.

This causes subsequent operations to use cached dentry information that
no longer matches the on-disk state. When a second rename targets the
same entry, VFS attempts to decrement i_nlink on the stale inode, which
may already have i_nlink=0, triggering a WARNING in drop_nlink().

Example sequence:
1. First rename (RENAME_WHITEOUT): file2 → file1
- f2fs updates file1 entry on disk (points to inode 8)
- f2fs deletes file2 entry on disk
- f2fs_add_link(whiteout) fails (corrupted directory)
- Returns error to VFS
- VFS does not call d_move() due to error
- VFS cache still has: file1 → inode 7 (stale!)
- inode 7 has i_nlink=0 (already decremented)

2. Second rename: file3 → file1
- VFS uses stale cache: file1 → inode 7
- Tries to drop_nlink on inode 7 (i_nlink already 0)
- WARNING in drop_nlink()

Fix this by explicitly invalidating old_dentry and new_dentry when
f2fs_add_link fails during whiteout creation. This forces VFS to
refresh from disk on subsequent operations, ensuring cache consistency
even when the rename partially succeeds.

Reproducer:
1. Mount F2FS image with corrupted i_current_depth
2. renameat2(file2, file1, RENAME_WHITEOUT)
3. renameat2(file3, file1, 0)
4. System triggers WARNING in drop_nlink()
Advisories

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Fixes

Solution

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Workaround

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History

Tue, 13 Jan 2026 15:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: f2fs: invalidate dentry cache on failed whiteout creation F2FS can mount filesystems with corrupted directory depth values that get runtime-clamped to MAX_DIR_HASH_DEPTH. When RENAME_WHITEOUT operations are performed on such directories, f2fs_rename performs directory modifications (updating target entry and deleting source entry) before attempting to add the whiteout entry via f2fs_add_link. If f2fs_add_link fails due to the corrupted directory structure, the function returns an error to VFS, but the partial directory modifications have already been committed to disk. VFS assumes the entire rename operation failed and does not update the dentry cache, leaving stale mappings. In the error path, VFS does not call d_move() to update the dentry cache. This results in new_dentry still pointing to the old inode (new_inode) which has already had its i_nlink decremented to zero. The stale cache causes subsequent operations to incorrectly reference the freed inode. This causes subsequent operations to use cached dentry information that no longer matches the on-disk state. When a second rename targets the same entry, VFS attempts to decrement i_nlink on the stale inode, which may already have i_nlink=0, triggering a WARNING in drop_nlink(). Example sequence: 1. First rename (RENAME_WHITEOUT): file2 → file1 - f2fs updates file1 entry on disk (points to inode 8) - f2fs deletes file2 entry on disk - f2fs_add_link(whiteout) fails (corrupted directory) - Returns error to VFS - VFS does not call d_move() due to error - VFS cache still has: file1 → inode 7 (stale!) - inode 7 has i_nlink=0 (already decremented) 2. Second rename: file3 → file1 - VFS uses stale cache: file1 → inode 7 - Tries to drop_nlink on inode 7 (i_nlink already 0) - WARNING in drop_nlink() Fix this by explicitly invalidating old_dentry and new_dentry when f2fs_add_link fails during whiteout creation. This forces VFS to refresh from disk on subsequent operations, ensuring cache consistency even when the rename partially succeeds. Reproducer: 1. Mount F2FS image with corrupted i_current_depth 2. renameat2(file2, file1, RENAME_WHITEOUT) 3. renameat2(file3, file1, 0) 4. System triggers WARNING in drop_nlink()
Title f2fs: invalidate dentry cache on failed whiteout creation
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-01-13T15:31:23.948Z

Reserved: 2026-01-13T15:30:19.647Z

Link: CVE-2025-71069

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-01-13T16:16:06.300

Modified: 2026-01-13T16:16:06.300

Link: CVE-2025-71069

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses

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