Executive brief
A vulnerability in the Linux kernel's OCFS2 file system could allow a local user to cause a system crash. The issue occurs during the process of unmounting a storage volume, where the system incorrectly attempts to access memory that has already been cleared. This results in a 'null pointer dereference' that triggers a kernel panic, leading to a denial of service.
Technical details
A null pointer dereference exists in the OCFS2 (Oracle Cluster File System 2) implementation within the Linux kernel. The vulnerability is located in the 'ocfs2_clear_inode' function. During a volume dismount ('ocfs2_dismount_volume'), 'ocfs2_journal_shutdown' is called, which sets 'osb->journal' to NULL. Subsequent calls in the dismount path, specifically 'jbd2_journal_release_jbd_inode', attempt to dereference this NULL pointer. A local attacker with sufficient privileges to trigger a dismount or manipulate file system inodes could cause a kernel panic (Denial of Service). The fix introduces a check to ensure 'osb->journal' is not NULL before proceeding with the release.
Affected products
- Linux Linux Kernel 5.16 to 6.1.151, 6.2 to 6.6.105, 6.7 to 6.12.46, 6.13 to 6.16.6
Timeline
- 2025-08-19: other: Patch authored
- 2025-09-19: disclosed: CVE published
- 2025-09-19: advisory
References
- https://git.kernel.org/stable/c/42c415c53ad2065088cc411d08925effa5b3d255
- https://git.kernel.org/stable/c/85e66331b60601d903cceaf8c10a234db863cd78
- https://git.kernel.org/stable/c/e9188f66e94955431ddbe2cd1cdf8ff2bb486abf
- https://git.kernel.org/stable/c/f46e8ef8bb7b452584f2e75337b619ac51a7cadf
- https://git.kernel.org/stable/c/f4a917e6cd6c798f7adf39907f117fc754db1283
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html