Executive brief
The OCFS2 file system component in the Linux kernel contained a circular locking dependency that could cause a system deadlock. When multiple file operations occur concurrently—such as creating files, writing data, and deleting inode orphans—the kernel could enter a state where threads wait indefinitely for locks held by each other, freezing affected systems and causing service unavailability.
Technical details
The vulnerability is a circular locking dependency (CWE-833 / deadlock) involving three system inodes in OCFS2: INODE_ALLOC, EXTENT_ALLOC, and ORPHAN_DIR. The issue occurs because ocfs2_dio_end_io_write() acquires EXTENT_ALLOC and then ORPHAN_DIR locks, while ocfs2_mknod() acquires INODE_ALLOC then EXTENT_ALLOC, and ocfs2_wipe_inode() acquires ORPHAN_DIR then INODE_ALLOC—creating a cycle. The fix releases allocation contexts (EXTENT_ALLOC) before acquiring ORPHAN_DIR in ocfs2_dio_end_io_write(). No precondition of elevated privilege or network access is required; the deadlock can be triggered by normal concurrent file operations on an OCFS2 file system. A patch is available in the Linux kernel.
Affected products
- Linux Linux kernel prior to patch
Timeline
- 2026-09-04: disclosed
- 2026-09-04: patched