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

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-17 · updated 2026-10-19

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).

Affected products

Linux kernel: from 6.6.79 before 6.6.157; from 6.12.13 before 6.12.110; from 6.13.2 before 6.14; 6.14 — fixed in 6.12.110, 6.14, 6.6.157, 7.3

How to fix

Upgrade to a fixed version: Linux kernel 6.12.110, 6.14, 6.6.157, 7.3. Check the vendor advisory for mitigations.

References

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