CVE-2025-21786

Summary

In the Linux kernel, the following vulnerability has been resolved:

workqueue: Put the pwq after detaching the rescuer from the pool

The commit 68f83057b913("workqueue: Reap workers via kthread_stop() and remove detach_completion") adds code to reap the normal workers but mistakenly does not handle the rescuer and also removes the code waiting for the rescuer in put_unbound_pool(), which caused a use-after-free bug reported by Cheung Wall.

To avoid the use-after-free bug, the pool’s reference must be held until the detachment is complete. Therefore, move the code that puts the pwq after detaching the rescuer from the pool.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux68f83057b913467a999e1bf9e0da6a119668f769 < e7c16028a424dd35be1064a68fa318be4359310faffected
LinuxLinux68f83057b913467a999e1bf9e0da6a119668f769 < 835b69c868f53f959d4986bbecd561ba6f38e492affected
LinuxLinux68f83057b913467a999e1bf9e0da6a119668f769 < e76946110137703c16423baf6ee177b751a34b7eaffected
LinuxLinux6.11affected
LinuxLinux0 < 6.11unaffected
LinuxLinux6.12.16 <= 6.12.*unaffected
LinuxLinux6.13.4 <= 6.13.*unaffected
LinuxLinux6.14 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

References