Vehicle: fix potential out-of-bound access when receiving SERIAL_CONTROL msg

ser.count could be set to a value > sizeof(ser.data).

src/Vehicle/Vehicle.cc

@@ -761,7 +761,12 @@ void Vehicle::_mavlinkMessageReceived(LinkInterface* link, mavlink_message_t mes
     {
         mavlink_serial_control_t ser;
         mavlink_msg_serial_control_decode(&message, &ser);
-        emit mavlinkSerialControl(ser.device, ser.flags, ser.timeout, ser.baudrate, QByteArray(reinterpret_cast<const char*>(ser.data), ser.count));
+        if (static_cast<size_t>(ser.count) > sizeof(ser.data)) {
+            qWarning() << "Invalid count for SERIAL_CONTROL, discarding." << ser.count;
+        } else {
+            emit mavlinkSerialControl(ser.device, ser.flags, ser.timeout, ser.baudrate,
+                    QByteArray(reinterpret_cast<const char*>(ser.data), ser.count));
+        }
     }
         break;