--- a/sys/dev/drm/amd/amdgpu/kv_dpm.c
+++ b/sys/dev/drm/amd/amdgpu/kv_dpm.c
@@ -162,10 +162,13 @@ static void sumo_construct_vid_mapping_table(struct amdgpu_device *adev,
 					     ATOM_AVAILABLE_SCLK_LIST *table)
 {
 	u32 i, j;
 
-	for (i = 0; i < SUMO_MAX_HARDWARE_POWERLEVELS; i++) {
-		if (table[i].ulSupportedSCLK != 0) {
+	/* usVoltageIndex is an untrusted USHORT from the VBIOS; entries[] only
+	 * has SUMO_MAX_NUMBER_VOLTAGES slots (kv_dpm.h). */
+	for (i = 0; i < SUMO_MAX_HARDWARE_POWERLEVELS; i++) {
+		if (table[i].ulSupportedSCLK != 0 &&
+		    table[i].usVoltageIndex < SUMO_MAX_NUMBER_VOLTAGES) {
 			vid_mapping_table->entries[table[i].usVoltageIndex].vid_7bit =
 				table[i].usVoltageID;
 			vid_mapping_table->entries[table[i].usVoltageIndex].vid_2bit =
 				table[i].usVoltageIndex;
 		}