[LTS 9.2] CVE-2025-21786

[pvts-mat]

[LTS 9.2]
CVE-2025-21786
VULN-54095

Problem

https://access.redhat.com/security/cve/CVE-2025-21786

A vulnerability was found in the Linux kernel's work queue subsystem, which manages background task execution. The issue stems from improper handling of the "rescuer" thread during the cleanup of unbound work queues.

Applicability: no

The CVE-2025-21786 does not apply to LTS 9.2. The argument follows the same logic as laid out in #406.

The history of the affected file kernel/workqueue.c in ciqlts9_2 is the same as in ciqlts9_4 with the following commits missing, which are not related to the bug in any way and mostly deal with workqueue's handling of the CPU isolation:

Mainline	LTS 9.4 backport
686f669	d4e81a6
ace3c54	4356616
ca10d85	bed8f3e
fe28f63	24be7e3
49277a5	6524bc7
4a6c560	1d28ea8

At the same time the bug, its root cause and its fix are all entirely contained in the kernel/workqueue.c file, so there is no need to check for version discrepancies anywhere else.

[pvts-mat]

The "draft" status is only to prevent accidental merge, the PR is ready for review.