put back the packet buffer when parsing the connection ID fails

packet_handler_map.go

@@ -273,6 +273,7 @@ func (h *packetHandlerMap) handlePacket(
 ) {
 	connID, err := wire.ParseConnectionID(data, h.connIDLen)
 	if err != nil {
+		buffer.MaybeRelease()
 		h.logger.Debugf("error parsing connection ID on packet from %s: %s", addr, err)
 		if h.tracer != nil {
 			h.tracer.DroppedPacket(addr, logging.PacketTypeNotDetermined, protocol.ByteCount(len(data)), logging.PacketDropHeaderParseError)