Executive brief
A vulnerability was identified in the Linux kernel's F2FS file system where corrupted internal identifiers (NIDs) could lead to system instability. This issue occurs when the file system encounters unexpected or out-of-range data on the disk, potentially causing errors during file allocation. Patches have been released to add sanity checks that detect and handle this corruption safely.
Technical details
A vulnerability in the F2FS (Flash-Friendly File System) component of the Linux kernel allowed for the processing of corrupted Node IDs (NIDs). Specifically, in the `free_nid_list`, the `footer.ino` and `footer.nid` could be identical and out-of-range, indicating on-disk corruption. Without proper validation, `f2fs_alloc_nid()` would attempt to use these invalid identifiers. The fix introduces a sanity check using `is_invalid_nid()` within `f2fs_alloc_nid()` to detect corruption. If an invalid NID is detected, the system now stops the checkpoint process with `STOP_CP_REASON_CORRUPTED_NID` to prevent further data inconsistency or kernel misbehavior.
Affected products
- Linux Linux Kernel f2fs file system component
Timeline
- 2025-08-07: other: Initial patch authored
- 2025-12-16: disclosed: CVE published
- 2025-11-13: patched: Patch committed to stable branches