void handle_incoming_vpn_data(int sock) {
	vpn_packet_t pkt;
	char *hostname;
	sockaddr_t from;
	socklen_t fromlen = sizeof(from);
	node_t *n;

	pkt.len = recvfrom(listen_socket[sock].udp, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);

	if(pkt.len < 0) {
		if(!sockwouldblock(sockerrno))
			logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
		return;
	}

	sockaddrunmap(&from);		/* Some braindead IPv6 implementations do stupid things. */

	n = lookup_node_udp(&from);

	if(!n) {
		n = try_harder(&from, &pkt);
		if(n)
			update_node_udp(n, &from);
		else ifdebug(PROTOCOL) {
			hostname = sockaddr2hostname(&from);
			logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
			free(hostname);
			return;
		}
		else
			return;
	}

	n->sock = sock;

	receive_udppacket(n, &pkt);
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.