CVE-2024-50019 kthread: unpark only parked kthread
A race condition in the Linux kernel's kthread handling can trigger a warning and potential instability when stopping per-CPU threads, requiring a kernel patch.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-50019?
CVE-2024-50019 is a medium-severity vulnerability in Linux kernel, published on 21 Oct 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
kthread: unpark only parked kthread
Calling into kthread unparking unconditionally is mostly harmless when the kthread is already unparked. The wake up is then simply ignored because the target is not in TASK_PARKED state.
However if the kthread is per CPU, the wake up is preceded by a call to kthread_bind() which expects the task to be inactive and in TASK_PARKED state, which obviously isn't the case if it is unparked.
As a result, calling kthread_stop() on an unparked per-cpu kthread triggers such a warning:
WARNING: CPU: 0 PID: 11 at kernel/kthread.c:525 __kthread_bind_mask kernel/kthread.c:525 <TASK> kthread_stop+0x17a/0x630 kernel/kthread.c:707 destroy_workqueue+0x136/0xc40 kernel/workqueue.c:5810 wg_destruct+0x1e2/0x2e0 drivers/net/wireguard/device.c:257 netdev_run_todo+0xe1a/0x1000 net/core/dev.c:10693 default_device_exit_batch+0xa14/0xa90 net/core/dev.c:11769 ops_exit_list net/core/net_namespace.c:178 [inline] cleanup_net+0x89d/0xcc0 net/core/net_namespace.c:640 process_one_work kernel/workqueue.c:3231 [inline] process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312 worker_thread+0x86d/0xd70 kernel/workqueue.c:3393 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK>
Fix this with skipping unecessary unparking while stopping a kthread.
Which versions are affected by CVE-2024-50019?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-50019?
Apply the vendor's patch.
Is CVE-2024-50019 being exploited?
There is no known exploitation of CVE-2024-50019 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-51453, AZL-51521, BELL-CVE-2024-50019, DEBIAN-CVE-2024-50019, GHSA-p957-6gfm-79hj, UBUNTU-CVE-2024-50019.