blk-mq: pop cached request if it is usable

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Summary

CVECVE-2026-64017
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-19 16:17:41 UTC
Updated2026-07-20 15:17:02 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001550000 probability, percentile 0.051030000 (date 2026-07-20)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected b0077e269f6c152e807fdac90b58caf012cdbaab 388468f7e7d1eab092cf2a39fdfb502e52019ec6 git Not specified
CNA Linux Linux affected b0077e269f6c152e807fdac90b58caf012cdbaab dc278e9bf2b9513a763353e6b9cc21e0f532954e git Not specified
CNA Linux Linux affected b5c8e0ff76d10f6bf70a7237678f27c20cf59bc9 git Not specified
CNA Linux Linux affected e9c309ded295b7f8849097d71ae231456ca79f78 git Not specified
CNA Linux Linux affected b80056bd75a16e4550873ecefe12bc8fd190b1cf git Not specified
CNA Linux Linux affected 33cf52b6e53a6aa55883aa7fb9ceffceff8488a6 git Not specified
CNA Linux Linux affected 8b6075046470c8756242dfe3fd058813636f69a3 git Not specified
CNA Linux Linux affected 6.1.72 6.2 semver Not specified
CNA Linux Linux affected 6.5.13 6.6 semver Not specified
CNA Linux Linux affected 6.6.3 6.7 semver Not specified
CNA Linux Linux affected 6.1.75 6.2 semver Not specified
CNA Linux Linux affected 6.6.14 6.7 semver Not specified
CNA Linux Linux affected 6.7 Not specified
CNA Linux Linux unaffected 6.7 semver Not specified
CNA Linux Linux unaffected 7.0.11 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/388468f7e7d1eab092cf2a39fdfb502e52019ec6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/dc278e9bf2b9513a763353e6b9cc21e0f532954e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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