Executive brief
A vulnerability was identified in the Linux kernel's F2FS file system during garbage collection processes. This issue can cause the system to crash (kernel bug) when handling certain data movements, particularly with encrypted files. An exploit would result in a complete system outage, impacting availability and potentially disrupting operations.
Technical details
A vulnerability in the F2FS file system's garbage collection (GC) mechanism leads to a kernel BUG (VM_BUG_ON_FOLIO) in 'folio_end_read'. The root cause is a race or logic error where 'ra_data_block' initiates I/O for a page that is already marked as 'uptodate' after being moved between block addresses. This typically occurs when a page is moved from address A to B, marked uptodate, and then moved again to address C. The fix introduces a check using 'folio_test_uptodate' within 'fs/f2fs/gc.c' to avoid redundant and invalid I/O submissions. This issue was discovered via fuzz testing and is similar to previously reported syzbot bugs regarding encrypted file corruption during GC.
Affected products
- Linux Linux Kernel f2fs file system
Timeline
- 2026-03-05: other: Patch authored
- 2026-05-23: patched: Patch committed to stable branches
- 2026-06-24: disclosed: CVE published