GHSA-RR92-7PJ4-8WHF
Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-17 18:32In 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.
{
"affected": [],
"aliases": [
"CVE-2026-93201"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:18:16Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: validate seg_id fields from persistent memory\n\ncache_pos_decode(), cache_key_decode() and the last-kset branches of\ncache_replay(), the writeback worker and the GC worker take a cache\nsegment id from the cache device metadata and index cache-\u003esegments[]\nwith it without checking it against cache-\u003en_segs. That metadata is only\nCRC-protected with a fixed public seed, so whoever supplies the cache\ndevice on a table load (CAP_SYS_ADMIN) controls the id; an out-of-range\nvalue forms a wild pcache_cache_segment pointer that is dereferenced and\nwritten through -- an out-of-bounds read and write driven by on-disk data.\n\nAdd cache_seg_id_valid() and reject an out-of-range id at each decode\nsite, failing the operation with -EIO instead of indexing past the array.\nBound the id against the initialized-segment count (cache_info.n_segs)\nrather than the physical device total. A forged cache_info.n_segs below\nseg_num otherwise leaves segments[cache_info.n_segs..seg_num) as zeroed\nstructs whose data pointer is NULL, so a forged id in that window would\nstill be dereferenced. A later patch guarantees cache_info.n_segs \u003c=\nseg_num, and a driver-created cache sets the two equal, so valid images\nare unaffected.",
"id": "GHSA-rr92-7pj4-8whf",
"modified": "2026-09-17T18:32:14Z",
"published": "2026-09-17T18:32:14Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93201"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/90c990a68460d7b5720e5634cf650eccdf0f4098"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b4bf8af5e7d7db4c5e179e15017da55857761ac4"
}
],
"schema_version": "1.4.0",
"severity": []
}
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