drm/xe/guc: Don't read data from G2H prior to length check

While highly unlikely, incoming G2H message might be too short
so we shouldn't read any data from it prior to checking a length.

Signed-off-by: Michal Wajdeczko <[e-mail]>
Cc: Matthew Brost <[e-mail]>
Reviewed-by: Matthew Brost <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/xe/xe_guc_submit.c

···
 int xe_guc_sched_done_handler(struct xe_guc *guc, u32 *msg, u32 len)
 {
 	struct xe_exec_queue *q;
-	u32 guc_id = msg[0];
-	u32 runnable_state = msg[1];
+	u32 guc_id, runnable_state;
 
 	if (unlikely(len < 2))
 		return -EPROTO;
+
+	guc_id = msg[0];
+	runnable_state = msg[1];
 
 	q = g2h_exec_queue_lookup(guc, guc_id);
 	if (unlikely(!q))
···
 int xe_guc_deregister_done_handler(struct xe_guc *guc, u32 *msg, u32 len)
 {
 	struct xe_exec_queue *q;
-	u32 guc_id = msg[0];
+	u32 guc_id;
 
 	if (unlikely(len < 1))
 		return -EPROTO;
+
+	guc_id = msg[0];
 
 	q = g2h_exec_queue_lookup(guc, guc_id);
 	if (unlikely(!q))
···
 {
 	struct xe_gt *gt = guc_to_gt(guc);
 	struct xe_exec_queue *q;
-	u32 guc_id = msg[0];
+	u32 guc_id;
 
 	if (unlikely(len < 1))
 		return -EPROTO;
+
+	guc_id = msg[0];
 
 	q = g2h_exec_queue_lookup(guc, guc_id);
 	if (unlikely(!q))
···
 {
 	struct xe_gt *gt = guc_to_gt(guc);
 	struct xe_exec_queue *q;
-	u32 guc_id = msg[0];
+	u32 guc_id;
 
 	if (unlikely(len < 1))
 		return -EPROTO;
+
+	guc_id = msg[0];
 
 	q = g2h_exec_queue_lookup(guc, guc_id);
 	if (unlikely(!q))