CVE-2025-71069

Description

In the Linux kernel, the following vulnerability has been resolved:f2fs: invalidate dentry cache on failed whiteout creationF2FS can mount filesystems with corrupted directory depth values thatget runtime-clamped to MAX_DIR_HASH_DEPTH. When RENAME_WHITEOUToperations are performed on such directories, f2fs_rename performsdirectory modifications (updating target entry and deleting sourceentry) before attempting to add the whiteout entry via f2fs_add_link.If f2fs_add_link fails due to the corrupted directory structure, thefunction returns an error to VFS, but the partial directorymodifications have already been committed to disk. VFS assumes theentire 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 dentrycache. 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 referencethe freed inode.This causes subsequent operations to use cached dentry information thatno longer matches the on-disk state. When a second rename targets thesame entry, VFS attempts to decrement i_nlink on the stale inode, whichmay 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 whenf2fs_add_link fails during whiteout creation. This forces VFS torefresh from disk on subsequent operations, ensuring cache consistencyeven when the rename partially succeeds.Reproducer:1. Mount F2FS image with corrupted i_current_depth2. renameat2(file2, file1, RENAME_WHITEOUT)3. renameat2(file3, file1, 0)4. System triggers WARNING in drop_nlink()

Risk Information

Associated Vulnerability

Patch Details

References

https://nvd.nist.gov/vuln/detail/CVE-2023-1234
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-1234