CVE-2025-40329 drm/sched: Fix deadlock in drm_sched_entity_kill_jobs_cb
A race condition in the Linux kernel's DRM scheduler can cause a deadlock, leading to a local denial of service.
- 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-2025-40329?
CVE-2025-40329 is a vulnerability in Linux, published on 9 Dec 2025. 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:
drm/sched: Fix deadlock in drm_sched_entity_kill_jobs_cb
The Mesa issue referenced below pointed out a possible deadlock:
[ 1231.611031] Possible interrupt unsafe locking scenario:
[ 1231.611033] CPU0 CPU1 [ 1231.611034] ---- ---- [ 1231.611035] lock(&xa->xa_lock#17); [ 1231.611038] local_irq_disable(); [ 1231.611039] lock(&fence->lock); [ 1231.611041] lock(&xa->xa_lock#17); [ 1231.611044] <Interrupt> [ 1231.611045] lock(&fence->lock); [ 1231.611047] *** DEADLOCK ***
In this example, CPU0 would be any function accessing job->dependencies through the xa_* functions that don't disable interrupts (eg: drm_sched_job_add_dependency(), drm_sched_entity_kill_jobs_cb()).
CPU1 is executing drm_sched_entity_kill_jobs_cb() as a fence signalling callback so in an interrupt context. It will deadlock when trying to grab the xa_lock which is already held by CPU0.
Replacing all xa_* usage by their xa_*_irq counterparts would fix this issue, but Christian pointed out another issue: dma_fence_signal takes fence.lock and so does dma_fence_add_callback.
dma_fence_signal() // locks f1.lock -> drm_sched_entity_kill_jobs_cb() -> foreach dependencies -> dma_fence_add_callback() // locks f2.lock
This will deadlock if f1 and f2 share the same spinlock.
To fix both issues, the code iterating on dependencies and re-arming them is moved out to drm_sched_entity_kill_jobs_work().
[phasta: commit message nits]
Which versions are affected by CVE-2025-40329?
How do I fix CVE-2025-40329?
Apply the vendor's patch.
Is CVE-2025-40329 being exploited?
There is no known exploitation of CVE-2025-40329 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40329, DEBIAN-CVE-2025-40329, GHSA-g9x6-c54r-8jg6, ROOT-OS-DEBIAN-13-CVE-2025-40329, ROOT-OS-UBUNTU-2404-CVE-2025-40329, UBUNTU-CVE-2025-40329.