What’s Vulnerable › Vulnerabilities

CVE-2026-31598: ocfs2: fix possible deadlock between unlink and dio_end_io_write

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-24 · updated 2026-10-19
• Weakness: CWE-667

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.

Affected products

• Linux kernel: from 4.6 before 6.6.136; from 6.7 before 6.12.83; from 6.13 before 6.18.24; from 6.19 before 6.19.14; from 7.0 before 7.0.1 — fixed in 6.12.83, 6.18.24, 6.19.14, 6.6.136, 7.0.1

How to fix

Upgrade to a fixed version: Linux kernel 6.12.83, 6.18.24, 6.19.14, 6.6.136. Check the vendor advisory for mitigations.

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

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