On 2023-04-05 12:37, Asahi Lina wrote:
> 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@xxxxxxxxxxxxx>
> ---
That's a good fix! Thanks for fixing this. I'll push
this through drm-misc-next and drm-misc-fixes, if there
are no objections.
Reviewed-by: Luben Tuikov <luben.tuikov@xxxxxxx>
Regards,
Luben
> drivers/gpu/drm/scheduler/sched_entity.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> index 15d04a0ec623..e0a8890a62e2 100644
> --- a/drivers/gpu/drm/scheduler/sched_entity.c
> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> @@ -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);
> }
>
> ---
> base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6
> change-id: 20230406-scheduler-uaf-2-44cf8faed245
>
> Thank you,
> ~~ Lina
>
