CVE-2026-64017

Technical Description

In 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

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References