From: Danilo Krummrich Date: Tue, 18 Apr 2023 10:04:53 +0000 (+0200) Subject: drm/scheduler: set entity to NULL in drm_sched_entity_pop_job() X-Git-Tag: v6.6.17~3937^2~23^2~442 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=96c7c2f4d5bd94b15fe63448c087f01607b56f4a;p=platform%2Fkernel%2Flinux-rpi.git drm/scheduler: set entity to NULL in drm_sched_entity_pop_job() It already happend a few times that patches slipped through which implemented access to an entity through a job that was already removed from the entities queue. Since jobs and entities might have different lifecycles, this can potentially cause UAF bugs. In order to make it obvious that a jobs entity pointer shouldn't be accessed after drm_sched_entity_pop_job() was called successfully, set the jobs entity pointer to NULL once the job is removed from the entity queue. Moreover, debugging a potential NULL pointer dereference is way easier than potentially corrupted memory through a UAF. Signed-off-by: Danilo Krummrich Link: https://lore.kernel.org/r/20230418100453.4433-1-dakr@redhat.com Reviewed-by: Luben Tuikov Signed-off-by: Luben Tuikov --- diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index e0a8890..3e2a31d8 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -448,6 +448,12 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity) drm_sched_rq_update_fifo(entity, next->submit_ts); } + /* Jobs and entities might have different lifecycles. Since we're + * removing the job from the entities queue, set the jobs entity pointer + * to NULL to prevent any future access of the entity through this job. + */ + sched_job->entity = NULL; + return sched_job; } diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c index f6801eb..c3582c4 100644 --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -42,6 +42,10 @@ * the hardware. * * The jobs in a entity are always scheduled in the order that they were pushed. + * + * Note that once a job was taken from the entities queue and pushed to the + * hardware, i.e. the pending queue, the entity must not be referenced anymore + * through the jobs entity pointer. */ #include