Executive brief
A vulnerability in the Linux kernel's F2FS file system could lead to file system corruption or inconsistency. During certain background maintenance tasks (Garbage Collection), the system may fail to properly clear internal markers on data blocks. This causes file system repair tools (fsck) to misinterpret the data, potentially leading to incorrect repairs or data management errors that affect system reliability.
Technical details
A vulnerability exists in the F2FS implementation within the Linux kernel where Foreground Garbage Collection (FGGC) fails to clear dentry and fsync marks during node block migration. When these marks persist incorrectly, the fsck utility may misinterpret migrated node blocks as valid user-issued fsync writes. This root cause stems from the GC process not clearing metadata flags in the `__write_node_folio` path during FGGC, unlike the Background Garbage Collection (BGGC) path. An attacker with local access could potentially trigger specific I/O patterns to induce this inconsistency, leading to file system corruption or denial of service. The fix involves moving the management of these marks into `__write_node_folio` to ensure they are consistently cleared during migration.
Affected products
- Linux Linux Kernel f2fs file system
Timeline
- 2026-05-28: disclosed
- 2026-05-28: advisory