GHSA-PQJQ-MHGH-J532
Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-20 15:31In the Linux kernel, the following vulnerability has been resolved:
blk-mq: pop cached request if it is usable
When submitting a bio to blk-mq, if the task should sleep after peeking a cached request, but before it pops it, the plug flushes and calls blk_mq_free_plug_rqs, freeing the cached_rqs. This creates a use-after-free bug. Fix this by popping the cached request before any possible blocking calls if it is suitable for use.
Popping this request first holds a queue reference, so avoid any serialization races with queue freezes and can safely proceed with dispatching that request to the driver. This potentially increases a timing window from when a driver wants to freeze its queue to when requests stop being dispatched. That scenario is off the fast path though, and drivers need to appropriately handle requests during a freeze request anyway.
The downside is the popped element needs to be individually freed when we performed a bio plug merge. The cached request would have had to be freed later anyway, but this patch does it inline with building the plug list instead of after flushing it.
{
"affected": [],
"aliases": [
"CVE-2026-64017"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-19T16:17:41Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nblk-mq: pop cached request if it is usable\n\nWhen submitting a bio to blk-mq, if the task should sleep after peeking\na cached request, but before it pops it, the plug flushes and calls\nblk_mq_free_plug_rqs, freeing the cached_rqs. This creates a\nuse-after-free bug. Fix this by popping the cached request before any\npossible blocking calls if it is suitable for use.\n\nPopping this request first holds a queue reference, so avoid any\nserialization races with queue freezes and can safely proceed with\ndispatching that request to the driver. This potentially increases a\ntiming window from when a driver wants to freeze its queue to when\nrequests stop being dispatched. That scenario is off the fast path\nthough, and drivers need to appropriately handle requests during a\nfreeze request anyway.\n\nThe downside is the popped element needs to be individually freed when\nwe performed a bio plug merge. The cached request would have had to be\nfreed later anyway, but this patch does it inline with building the plug\nlist instead of after flushing it.",
"id": "GHSA-pqjq-mhgh-j532",
"modified": "2026-07-20T15:31:55Z",
"published": "2026-07-19T18:31:49Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64017"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/388468f7e7d1eab092cf2a39fdfb502e52019ec6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dc278e9bf2b9513a763353e6b9cc21e0f532954e"
}
],
"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"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
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Nomenclature
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- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.