[PATCH 3/4] drm/xe/guc: Don't read data from G2H prior to length check

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

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 <michal.wajdeczko@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
---
 drivers/gpu/drm/xe/xe_guc_submit.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 4481890be941..147000fd1177 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1885,12 +1885,14 @@ static void handle_sched_done(struct xe_guc *guc, struct xe_exec_queue *q,
 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))
 		return -EPROTO;
@@ -1924,11 +1926,13 @@ static void handle_deregister_done(struct xe_guc *guc, struct xe_exec_queue *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))
 		return -EPROTO;
@@ -1950,11 +1954,13 @@ int xe_guc_exec_queue_reset_handler(struct xe_guc *guc, u32 *msg, u32 len)
 {
 	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))
 		return -EPROTO;
@@ -2010,11 +2016,13 @@ int xe_guc_exec_queue_memory_cat_error_handler(struct xe_guc *guc, u32 *msg,
 {
 	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))
 		return -EPROTO;
-- 
2.43.0