int sctp_inet_listen(struct socket *sock, int backlog)
{
	struct sock *sk = sock->sk;
	struct sctp_endpoint *ep = sctp_sk(sk)->ep;
	int err = -EINVAL;

	if (unlikely(backlog < 0))
		return err;

	lock_sock(sk);

	/* Peeled-off sockets are not allowed to listen().  */
	if (sctp_style(sk, UDP_HIGH_BANDWIDTH))
		goto out;

	if (sock->state != SS_UNCONNECTED)
		goto out;

	if (!sctp_sstate(sk, LISTENING) && !sctp_sstate(sk, CLOSED))
		goto out;

	/* If backlog is zero, disable listening. */
	if (!backlog) {
		if (sctp_sstate(sk, CLOSED))
			goto out;

		err = 0;
		sctp_unhash_endpoint(ep);
		sk->sk_state = SCTP_SS_CLOSED;
		if (sk->sk_reuse)
			sctp_sk(sk)->bind_hash->fastreuse = 1;
		goto out;
	}

	/* If we are already listening, just update the backlog */
	if (sctp_sstate(sk, LISTENING))
		sk->sk_max_ack_backlog = backlog;
	else {
		err = sctp_listen_start(sk, backlog);
		if (err)
			goto out;
	}

	err = 0;
out:
	release_sock(sk);
	return err;
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.