CVE-2026-31598

Description

In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix possible deadlock between unlink and dio_end_io_write ocfs2_unlink takes orphan dir inode_lock first and then ip_alloc_sem, while in ocfs2_dio_end_io_write, it acquires these locks in reverse order. This creates an ABBA lock ordering violation on lock classes ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE] and ocfs2_file_ip_alloc_sem_key. Lock Chain #0 (orphan dir inode_lock -> ip_alloc_sem): ocfs2_unlink ocfs2_prepare_orphan_dir ocfs2_lookup_lock_orphan_dir inode_lock(orphan_dir_inode) <- lock A __ocfs2_prepare_orphan_dir ocfs2_prepare_dir_for_insert ocfs2_extend_dir ocfs2_expand_inline_dir down_write(&oi->ip_alloc_sem) <- Lock B Lock Chain #1 (ip_alloc_sem -> orphan dir inode_lock): ocfs2_dio_end_io_write down_write(&oi->ip_alloc_sem) <- Lock B ocfs2_del_inode_from_orphan() inode_lock(orphan_dir_inode) <- Lock A Deadlock Scenario: CPU0 (unlink) CPU1 (dio_end_io_write) ------ ------ inode_lock(orphan_dir_inode) down_write(ip_alloc_sem) down_write(ip_alloc_sem) inode_lock(orphan_dir_inode) Since ip_alloc_sem is to protect allocation changes, which is unrelated with operations in ocfs2_del_inode_from_orphan. So move ocfs2_del_inode_from_orphan out of ip_alloc_sem to fix the deadlock.

Predictions

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

References

• https://git.kernel.org/stable/c/2b884d52273c60c298bd570163e8053657bbaff6
• https://git.kernel.org/stable/c/4b80b5a838a32437f2cae0662578bac216a2c51a
• https://git.kernel.org/stable/c/b02da26a992db0c0e2559acbda0fc48d4a2fd337
• https://git.kernel.org/stable/c/bc0fb5c7d54c78be43a536df0e20dee32adb27d3
• https://git.kernel.org/stable/c/e049f7a9bd80b7319590789ea5e1c523d6339d91
• https://git.kernel.org/stable/c/f9fb1a7b635849322e1d7b7b6b26389778ec8e82
• https://www.suse.com/security/cve/CVE-2026-31598.html
• https://security-tracker.debian.org/tracker/CVE-2026-31598

CWEs

CWE-667