[PATCH] drm/sched: Fix UB pointer dereference

[Philipp Stanner]

In drm_sched_job_init(), commit 56e449603f0a ("drm/sched: Convert the
GPU scheduler to variable number of run-queues") implemented a call to
drm_err(), which uses the job's scheduler pointer as a parameter.
job->sched, however, is not yet valid as it gets set by
drm_sched_job_arm(), which is always called after drm_sched_job_init().

Since the scheduler code has no control over how the API-User has
allocated or set 'job', the pointer's dereference is undefined behavior.

Fix the UB by replacing drm_err() with pr_err().

Cc: <stable@xxxxxxxxxxxxxxx>	# 6.7+
Fixes: 56e449603f0a ("drm/sched: Convert the GPU scheduler to variable number of run-queues")
Reported-by: Danilo Krummrich <dakr@xxxxxxxxxx>
Closes: https://lore.kernel.org/lkml/20231108022716.15250-1-dakr@xxxxxxxxxx/
Signed-off-by: Philipp Stanner <pstanner@xxxxxxxxxx>
---
 drivers/gpu/drm/scheduler/sched_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 7e90c9f95611..356c30fa24a8 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -797,7 +797,7 @@ int drm_sched_job_init(struct drm_sched_job *job,
 		 * or worse--a blank screen--leave a trail in the
 		 * logs, so this can be debugged easier.
 		 */
-		drm_err(job->sched, "%s: entity has no rq!\n", __func__);
+		pr_err("*ERROR* %s: entity has no rq!\n", __func__);
 		return -ENOENT;
 	}
 
-- 
2.46.0