drm/amd/display: Check msg_id before processing transcation

[WHY & HOW]
HDCP_MESSAGE_ID_INVALID (-1) is not a valid msg_id nor is it a valid
array index, and it needs checking before used.

This fixes 4 OVERRUN issues reported by Coverity.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/hdcp/hdcp_msg.c

@@ -128,13 +128,21 @@ static bool hdmi_14_process_transaction(
 	const uint8_t hdcp_i2c_addr_link_primary = 0x3a; /* 0x74 >> 1*/
 	const uint8_t hdcp_i2c_addr_link_secondary = 0x3b; /* 0x76 >> 1*/
 	struct i2c_command i2c_command;
-	uint8_t offset = hdcp_i2c_offsets[message_info->msg_id];
+	uint8_t offset;
 	struct i2c_payload i2c_payloads[] = {
-		{ true, 0, 1, &offset },
+		{ true, 0, 1, 0 },
 		/* actual hdcp payload, will be filled later, zeroed for now*/
 		{ 0 }
 	};
 
+	if (message_info->msg_id == HDCP_MESSAGE_ID_INVALID) {
+		DC_LOG_ERROR("%s: Invalid message_info msg_id - %d\n", __func__, message_info->msg_id);
+		return false;
+	}
+
+	offset = hdcp_i2c_offsets[message_info->msg_id];
+	i2c_payloads[0].data = &offset;
+
 	switch (message_info->link) {
 	case HDCP_LINK_SECONDARY:
 		i2c_payloads[0].address = hdcp_i2c_addr_link_secondary;
@@ -308,6 +316,11 @@ static bool dp_11_process_transaction(
 	struct dc_link *link,
 	struct hdcp_protection_message *message_info)
 {
+	if (message_info->msg_id == HDCP_MESSAGE_ID_INVALID) {
+		DC_LOG_ERROR("%s: Invalid message_info msg_id - %d\n", __func__, message_info->msg_id);
+		return false;
+	}
+
 	return dpcd_access_helper(
 		link,
 		message_info->length,