| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2025-21786: workqueue: Put the pwq after detaching the rescuer from the pool |
| |
| Description |
| =========== |
| |
| 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. |
| |
| The Linux kernel CVE team has assigned CVE-2025-21786 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.11 with commit 68f83057b913467a999e1bf9e0da6a119668f769 and fixed in 6.12.16 with commit e7c16028a424dd35be1064a68fa318be4359310f |
| Issue introduced in 6.11 with commit 68f83057b913467a999e1bf9e0da6a119668f769 and fixed in 6.13.4 with commit 835b69c868f53f959d4986bbecd561ba6f38e492 |
| Issue introduced in 6.11 with commit 68f83057b913467a999e1bf9e0da6a119668f769 and fixed in 6.14 with commit e76946110137703c16423baf6ee177b751a34b7e |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2025-21786 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| kernel/workqueue.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/e7c16028a424dd35be1064a68fa318be4359310f |
| https://git.kernel.org/stable/c/835b69c868f53f959d4986bbecd561ba6f38e492 |
| https://git.kernel.org/stable/c/e76946110137703c16423baf6ee177b751a34b7e |
