Executive brief
The Linux kernel's f2fs filesystem contains a logic error in node footer validation that causes incorrect sanity checking of node identifiers. This could allow an attacker to bypass filesystem integrity checks, potentially leading to filesystem corruption or data loss when processing malformed filesystem metadata.
Technical details
The vulnerability is a logic error in the f2fs_sanity_check_node_footer() function called from __write_node_folio(). The function was being passed an incorrect parameter: a pre-calculated node ID (nid) instead of the folio page index. This causes the function to repeatedly check the same node ID rather than validating the correct node footer, bypassing sanity checks on filesystem metadata. The fix changes the function call to pass folio->index instead of nid. The vulnerability affects the f2fs filesystem module in the Linux kernel and is triggered during node folio write operations when sanity checking is performed on node footers.
Affected products
- Linux Linux kernel multiple versions (see kernel.org stable trees)
Timeline
- 2026-09-16: disclosed: Published on NVD
- 2026-08-06: patched: Fix committed upstream by Chao Yu
- 2026-09-11: patched: Fix included in stable kernel releases