CVE-2026-90279

/// Technical 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).

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References