md/raid5: round bitmap stripes with sector division

Summary

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).

Timeline

1. Sep 17, 2026, 4:08 PM UTCCVE published
2. Oct 19, 2026, 9:00 AM UTCRecord last updated

Affected versions

• Linux 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 Linux

  6.14

• KernelLinux

  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

References 5