CVE-2026-31598

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.

Weakness

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Affected Software

Extended Description

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/25.html
• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/27.html

References

• https://git.kernel.org/stable/c/297d8d7bb6a2bf133d3a3636edbdf94101cbd719
• https://git.kernel.org/stable/c/2b884d52273c60c298bd570163e8053657bbaff6
• https://git.kernel.org/stable/c/32630dee18c6bb2175c8a865a474749492eaf19c
• https://git.kernel.org/stable/c/4b80b5a838a32437f2cae0662578bac216a2c51a
• https://git.kernel.org/stable/c/93f35419eb84d58820040642cb6e7528fe4aba7a
• 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