drm/xe: Free job before xe_exec_queue_put

Free job depends on job->vm being valid, the last xe_exec_queue_put can
destroy the VM. Prevent UAF by freeing job before xe_exec_queue_put.

Fixes: dd08ebf ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Brost <[email protected]>
Reviewed-by: Nirmoy Das <[email protected]>
Reviewed-by: Jagmeet Randhawa <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit 32a42c9)
Signed-off-by: Rodrigo Vivi <[email protected]>

Author: mbrost05

drivers/gpu/drm/xe/xe_sched_job.c

@@ -171,12 +171,13 @@ void xe_sched_job_destroy(struct kref *ref)
 	struct xe_sched_job *job =
 		container_of(ref, struct xe_sched_job, refcount);
 	struct xe_device *xe = job_to_xe(job);
+	struct xe_exec_queue *q = job->q;
 
 	xe_sched_job_free_fences(job);
-	xe_exec_queue_put(job->q);
 	dma_fence_put(job->fence);
 	drm_sched_job_cleanup(&job->drm);
 	job_free(job);
+	xe_exec_queue_put(q);
 	xe_pm_runtime_put(xe);
 }