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drm/scheduler: Fix UAF race in drm_sched_entity_push_job() 

After a job is pushed into the queue, it is owned by the scheduler core
and may be freed at any time, so we can't write nor read the submit
timestamp after that point.

Fixes oopses observed with the drm/asahi driver, found with kASAN.

Signed-off-by: Asahi Lina <lina@asahilina.net>
Link: https://lore.kernel.org/r/20230406-scheduler-uaf-2-v1-1-972531cf0a81@asahilina.net
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
This commit is contained in:
Asahi Lina 2023-04-06 01:37:39 +09:00 committed by Luben Tuikov
parent 0ec8671837
commit 1e1d3574e6
1 changed files with 9 additions and 2 deletions
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11
drivers/gpu/drm/scheduler/sched_entity.c
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@ -507,12 +507,19 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
{
struct drm_sched_entity *entity = sched_job->entity;
bool first;
ktime_t submit_ts;
trace_drm_sched_job(sched_job, entity);
atomic_inc(entity->rq->sched->score);
WRITE_ONCE(entity->last_user, current->group_leader);
/*
* After the sched_job is pushed into the entity queue, it may be
* completed and freed up at any time. We can no longer access it.
* Make sure to set the submit_ts first, to avoid a race.
*/
sched_job->submit_ts = submit_ts = ktime_get();
first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
sched_job->submit_ts = ktime_get();
/* first job wakes up scheduler */
if (first) {
@ -529,7 +536,7 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
spin_unlock(&entity->rq_lock);
if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
drm_sched_rq_update_fifo(entity, sched_job->submit_ts);
drm_sched_rq_update_fifo(entity, submit_ts);
drm_sched_wakeup(entity->rq->sched);
}