Reviewed-by: Luben Tuikov <luben.tui...@amd.com> and applied to drm-misc-next.
Thanks! Regards, Luben On 2023-04-18 06:04, Danilo Krummrich wrote: > 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 <d...@redhat.com> > --- > drivers/gpu/drm/scheduler/sched_entity.c | 6 ++++++ > drivers/gpu/drm/scheduler/sched_main.c | 4 ++++ > 2 files changed, 10 insertions(+) > > diff --git a/drivers/gpu/drm/scheduler/sched_entity.c > b/drivers/gpu/drm/scheduler/sched_entity.c > index 15d04a0ec623..a9c6118e534b 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 9b16480686f6..e89a3e469cd5 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 <linux/kthread.h>
