Executive brief
A vulnerability in the Linux kernel's RAID management component could allow a local user to crash the system. The issue occurs when the system attempts to collect statistics for certain disk configurations, leading to a kernel 'Oops' or General Protection Fault. This primarily impacts system availability, potentially causing a denial-of-service on affected servers or workstations.
Technical details
A vulnerability exists in the md/md-bitmap component of the Linux kernel due to an improper check for a valid superblock in the bitmap_get_stats() function. Specifically, the code failed to verify the existence of a superblock for external bitmaps before attempting to access it, leading to a General Protection Fault (GPF) when reading from the proc filesystem (e.g., via seq_read). A local attacker with sufficient privileges to trigger statistics collection can cause a kernel panic (denial of service). The fix involves ensuring the existence of a superblock is checked for both internal and external bitmap cases. Patches have been released for various stable kernel branches including 6.1, 6.6, 6.12, and 6.15.
Affected products
- Linux Linux Kernel 6.1.135 to 6.1.146, 6.6.88 to 6.6.99, 6.12.25 to 6.12.39, 6.14.4 to 6.15, 6.15.1 to 6.15.7
Timeline
- 2025-07-25: disclosed: Initial publication of the vulnerability
- 2025-07-17: patched: Commits applied to stable kernel trees
References
- https://git.kernel.org/stable/c/3d82a729530bd2110ba66e4a1f73461c776edec2
- https://git.kernel.org/stable/c/3e0542701b37aa25b025d8531583458e4f014c2e
- https://git.kernel.org/stable/c/a18f9b08c70e10ea3a897058fee8a4f3b4c146ec
- https://git.kernel.org/stable/c/a23b16ba3274961494f5ad236345d238364349ff
- https://git.kernel.org/stable/c/c17fb542dbd1db745c9feac15617056506dd7195
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html