Executive brief
A stability issue was identified in the Linux kernel's network filesystem (netfs) component. Under specific conditions during file write operations, the system may encounter a kernel crash (BUG), leading to a denial of service. This primarily affects systems using network-backed storage like Ceph.
Technical details
A vulnerability exists in the Linux kernel's netfs subsystem within the netfs_write_begin() function. The issue is characterized by a VM_BUG_ON_FOLIO() assertion failure occurring at mm/filemap.c:1504, specifically when folio_test_locked(folio) returns false during a folio_unlock operation. This indicates a synchronization or locking state inconsistency during write operations on network filesystems (observed with ceph_aops). An attacker with local access could potentially trigger this crash by performing specific file stress operations, resulting in a kernel panic (Oops) and system unavailability. Patches have been released across multiple stable kernel branches.
Affected products
- Linux Linux Kernel 7.0.0-rc1
Timeline
- 2026-05-12: other: Patch authored
- 2026-06-01: patched: Patch committed to stable tree
- 2026-07-19: disclosed: CVE published