Bug 2559760 (CVE-2026-99058)

Summary: CVE-2026-99058 kernel: workqueue: Fix NULL current_pwq deref in chained work check
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's workqueue subsystem. A local user can cause a Denial of Service (DoS) through a system crash by queueing work onto a workqueue that is being drained or destroyed. This issue occurs because the kernel fails to verify that a worker thread is actively executing work before evaluating chained tasks, resulting in a NULL pointer dereference.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-10-23 13:32:02 UTC 
In the Linux kernel, the following vulnerability has been resolved:

workqueue: Fix NULL current_pwq deref in chained work check

current_wq_worker() only tells us that %current is a kworker. It does
not guarantee that the worker is currently executing a work item, as
worker->current_pwq is populated only while process_one_work() is running
the work function.

is_chained_work() can be reached while queueing on a draining or
destroying workqueue. If a kworker outside work-item execution reaches
that path, current_wq_worker() returns a worker but worker->current_pwq is
NULL, and the chained-work test can fault before it emits the intended
warning.

Guard the chained-work test with worker->current_pwq. A kworker without
current_pwq is not executing work on the target workqueue, so the helper
should return false and let the draining/destroying warning fire.
Comment 1 gkamathe 2026-10-27 03:18:07 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-99058.mbox