dm-pcache: validate seg_id fields from persistent memory

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-93201
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:18:16 UTC
Updated2026-09-17 17:18:16 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: dm-pcache: validate seg_id fields from persistent memory cache_pos_decode(), cache_key_decode() and the last-kset branches of cache_replay(), the writeback worker and the GC worker take a cache segment id from the cache device metadata and index cache->segments[] with it without checking it against cache->n_segs. That metadata is only CRC-protected with a fixed public seed, so whoever supplies the cache device on a table load (CAP_SYS_ADMIN) controls the id; an out-of-range value forms a wild pcache_cache_segment pointer that is dereferenced and written through -- an out-of-bounds read and write driven by on-disk data. Add cache_seg_id_valid() and reject an out-of-range id at each decode site, failing the operation with -EIO instead of indexing past the array. Bound the id against the initialized-segment count (cache_info.n_segs) rather than the physical device total. A forged cache_info.n_segs below seg_num otherwise leaves segments[cache_info.n_segs..seg_num) as zeroed structs whose data pointer is NULL, so a forged id in that window would still be dereferenced. A later patch guarantees cache_info.n_segs <= seg_num, and a driver-created cache sets the two equal, so valid images are unaffected.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 b4bf8af5e7d7db4c5e179e15017da55857761ac4 git Not specified
CNA Linux Linux affected 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 90c990a68460d7b5720e5634cf650eccdf0f4098 git Not specified
CNA Linux Linux affected 6.18 Not specified
CNA Linux Linux unaffected 6.18 semver Not specified
CNA Linux Linux unaffected 7.2.6 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b4bf8af5e7d7db4c5e179e15017da55857761ac4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/90c990a68460d7b5720e5634cf650eccdf0f4098 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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