ata: libata: cancel pending work after clearing deferred_qc

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Summary

CVECVE-2026-23355
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-25 11:16:34 UTC
Updated2026-04-24 19:13:44 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ata: libata: cancel pending work after clearing deferred_qc Syzbot reported a WARN_ON() in ata_scsi_deferred_qc_work(), caused by ap->ops->qc_defer() returning non-zero before issuing the deferred qc. ata_scsi_schedule_deferred_qc() is called during each command completion. This function will check if there is a deferred QC, and if ap->ops->qc_defer() returns zero, meaning that it is possible to queue the deferred qc at this time (without being deferred), then it will queue the work which will issue the deferred qc. Once the work get to run, which can potentially be a very long time after the work was scheduled, there is a WARN_ON() if ap->ops->qc_defer() returns non-zero. While we hold the ap->lock both when assigning and clearing deferred_qc, and the work itself holds the ap->lock, the code currently does not cancel the work after clearing the deferred qc. This means that the following scenario can happen: 1) One or several NCQ commands are queued. 2) A non-NCQ command is queued, gets stored in ap->deferred_qc. 3) Last NCQ command gets completed, work is queued to issue the deferred qc. 4) Timeout or error happens, ap->deferred_qc is cleared. The queued work is currently NOT canceled. 5) Port is reset. 6) One or several NCQ commands are queued. 7) A non-NCQ command is queued, gets stored in ap->deferred_qc. 8) Work is finally run. Yet at this time, there is still NCQ commands in flight. The work in 8) really belongs to the non-NCQ command in 2), not to the non-NCQ command in 7). The reason why the work is executed when it is not supposed to, is because it was never canceled when ap->deferred_qc was cleared in 4). Thus, ensure that we always cancel the work after clearing ap->deferred_qc. Another potential fix would have been to let ata_scsi_deferred_qc_work() do nothing if ap->ops->qc_defer() returns non-zero. However, canceling the work when clearing ap->deferred_qc seems slightly more logical, as we hold the ap->lock when clearing ap->deferred_qc, so we know that the work cannot be holding the lock. (The function could be waiting for the lock, but that is okay since it will do nothing if ap->deferred_qc is not set.)

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

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

Problem Types: NVD-CWE-noinfo

CVSS v3.1 Breakdown

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

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected ce22aaed011206fed9cbd8c9c2d44718607f31ee 0d12453818c35e1ded84633152c6b05002ae48b9 git Not specified
CNA Linux Linux affected 888cd7e40adb2ef4af1b4d3b6e2e83ad409ae8c2 6c5e8f16b5e8e614e829aaf38619bdd79107bb0a git Not specified
CNA Linux Linux affected 5d61a38a60e62750526d94663b69b7ac5c7f07a5 58e658763ba2aa9168d8516b98a6314d7461a53e git Not specified
CNA Linux Linux affected 0ea84089dbf62a92dc7889c79e6b18fc89260808 aac9b27f7c1f2b2cf7f50a9ca633ecbbcaf22af9 git Not specified
CNA Linux Linux affected 33abac5b5a5303ba2c66d89e063a806033be07fc git Not specified
CNA Linux Linux affected 21e0d7a15a789e99be89231dae25cb6ffc482a7c git Not specified
CNA Linux Linux affected 6.18.14 6.18.18 semver Not specified
CNA Linux Linux affected 6.19.4 6.19.7 semver Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/aac9b27f7c1f2b2cf7f50a9ca633ecbbcaf22af9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/6c5e8f16b5e8e614e829aaf38619bdd79107bb0a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/58e658763ba2aa9168d8516b98a6314d7461a53e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/0d12453818c35e1ded84633152c6b05002ae48b9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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