drm/v3d: Serialize the scheduler timeout handlers

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74638
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:37 UTC
Updated2026-08-25 06:18:43 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: drm/v3d: Serialize the scheduler timeout handlers V3D exposes several independent hardware queues (BIN, RENDER, TFU and CSD) but has only a single, global reset. A timeout on any one queue therefore has to stop, reset and restart the schedulers of every other queue as well. That makes concurrent timeout handlers unsafe. `reset_lock` was never able to make them safe, as a driver-side lock can only cover the driver's &drm_sched_backend_ops.timedout_job callback. The scheduler handles the timed out job and its pending list around that callback, outside of the driver's control, so a global reset triggered by one queue can still interfere with another queue that is in the middle of handling a timeout of its own. Consequently, if a reset happens in the CSD queue while a CL-intensive application is running, the global reset stops and restarts the CL queue's scheduler while that queue is handling a timeout of its own. As drm_sched_stop() and drm_sched_start() subtract and add the credits of every job sitting on the pending list of the scheduler they are called on, and as the CL queue's handler concurrently takes its job off that same list and puts it back, the stop and the start no longer see the same set of jobs. The CL queue is left with more credits in flight than its limit: [ 327.302739] ------------[ cut here ]------------ [ 327.302744] WARNING: CPU: 2 PID: 43 at drivers/gpu/drm/scheduler/sched_main.c:102 drm_sched_run_job_work+0x238/0x4d0 [gpu_sched] [ 327.302884] CPU: 2 UID: 0 PID: 43 Comm: kworker/u16:1 Not tainted 6.18.39-v8-16k+ #3 PREEMPT [ 327.302889] Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT) [ 327.302893] Workqueue: v3d_bin drm_sched_run_job_work [gpu_sched] [ 327.302984] Call trace: [ 327.302987] drm_sched_run_job_work+0x238/0x4d0 [gpu_sched] (P) [ 327.302997] process_scheduled_works+0x180/0x3d0 [ 327.303010] worker_thread+0x268/0x3e8 [ 327.303016] kthread+0x140/0x250 [ 327.303022] ret_from_fork+0x10/0x20 [ 327.303031] ---[ end trace 0000000000000000 ]--- From that point on, the credit count of the CL queue is broken, causing a complete GPU hang and UI freeze. The DRM scheduler already provides a mechanism to serialize the timeout handlers of different schedulers: an ordered workqueue passed as drm_sched_init()'s @timeout_wq parameter. By default, each scheduler queues its timeout work on the system workqueue, which runs the handlers concurrently. Give all of the queues a shared ordered workqueue instead, as recommended by the DRM scheduler documentation for hardware that has distinct queues but resets globally.

Risk And Classification

EPSS: 0.001660000 probability, percentile 0.060410000 (date 2026-08-25)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 35e4079bf1a2570abffce6ababa631afcf8ea0e5 5884851a096d8afcdf91f0e542bac193035183a6 git Not specified
CNA Linux Linux affected 35e4079bf1a2570abffce6ababa631afcf8ea0e5 c22a45817b9c92aa0391db60e2ed467c7e6027d7 git Not specified
CNA Linux Linux affected 35e4079bf1a2570abffce6ababa631afcf8ea0e5 4da94744707b27a3ae1197bdd7127da4505dc5b1 git Not specified
CNA Linux Linux affected 5235b56b7e5449d990d21d78723b1a5e7bb5738e git Not specified
CNA Linux Linux affected 12125f7d9c15e6d8ac91d10373b2db2f17dcf767 git Not specified
CNA Linux Linux affected a5f162727b91e480656da1876247a91f651f76de git Not specified
CNA Linux Linux affected 422a8b10ba42097a704d6909ada2956f880246f2 git Not specified
CNA Linux Linux affected 6.1.139 6.2 semver Not specified
CNA Linux Linux affected 6.6.91 6.7 semver Not specified
CNA Linux Linux affected 6.12.29 6.13 semver Not specified
CNA Linux Linux affected 6.14.7 6.15 semver Not specified
CNA Linux Linux affected 6.15 Not specified
CNA Linux Linux unaffected 6.15 semver Not specified
CNA Linux Linux unaffected 6.18.45 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/4da94744707b27a3ae1197bdd7127da4505dc5b1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c22a45817b9c92aa0391db60e2ed467c7e6027d7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5884851a096d8afcdf91f0e542bac193035183a6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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