GHSA-7HFQ-329H-84PC
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-13 09:32In the Linux kernel, the following vulnerability has been resolved:
dm-pcache: validate kset key_num and intra-segment bounds
Two more fields decoded from the cache device go unbounded. The kset key_num drives cache_kset_crc() and the replay loop in cache_replay(), the writeback worker and the GC worker, but only the magic and a fixed-seed CRC are checked first, so a non-last kset whose key_num exceeds the PCACHE_KSET_KEYS_MAX buffer reads past its end before the CRC compare. A key's intra-segment offset and length in cache_key_decode() are taken verbatim, so a key running past its segment is replayed into the cache tree and the data CRC check and every later read hit then copy adjacent persistent memory into the caller's bio -- an out-of-bounds read that leaks to user space. Both fields are controlled by whoever supplies the cache device (CAP_SYS_ADMIN); the CRC seed is public.
Add kset_onmedia_valid() to bound key_num before any kset read, and reject a key whose offset plus length, computed in 64 bits, exceeds the segment data_size. Valid metadata is unaffected.
{
"affected": [],
"aliases": [
"CVE-2026-80961"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:01Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm-pcache: validate kset key_num and intra-segment bounds\n\nTwo more fields decoded from the cache device go unbounded. The kset\nkey_num drives cache_kset_crc() and the replay loop in cache_replay(),\nthe writeback worker and the GC worker, but only the magic and a\nfixed-seed CRC are checked first, so a non-last kset whose key_num exceeds\nthe PCACHE_KSET_KEYS_MAX buffer reads past its end before the CRC compare.\nA key\u0027s intra-segment offset and length in cache_key_decode() are taken\nverbatim, so a key running past its segment is replayed into the cache\ntree and the data CRC check and every later read hit then copy adjacent\npersistent memory into the caller\u0027s bio -- an out-of-bounds read that\nleaks to user space. Both fields are controlled by whoever supplies the\ncache device (CAP_SYS_ADMIN); the CRC seed is public.\n\nAdd kset_onmedia_valid() to bound key_num before any kset read, and\nreject a key whose offset plus length, computed in 64 bits, exceeds the\nsegment data_size. Valid metadata is unaffected.",
"id": "GHSA-7hfq-329h-84pc",
"modified": "2026-09-13T09:32:09Z",
"published": "2026-09-11T21:31:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80961"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5ac38f4b4862fad6e7270fde5c3356a822ce74ca"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d8caf96040a06096276ab72f5e1e8547c014c564"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f11deb032fd84081e7831cffcba895d893054a22"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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