static int ipx_create(struct net *net, struct socket *sock, int protocol,
		      int kern)
{
	int rc = -ESOCKTNOSUPPORT;
	struct sock *sk;

	if (!net_eq(net, &init_net))
		return -EAFNOSUPPORT;

	/*
	 * SPX support is not anymore in the kernel sources. If you want to
	 * ressurrect it, completing it and making it understand shared skbs,
	 * be fully multithreaded, etc, grab the sources in an early 2.5 kernel
	 * tree.
	 */
	if (sock->type != SOCK_DGRAM)
		goto out;

	rc = -ENOMEM;
	sk = sk_alloc(net, PF_IPX, GFP_KERNEL, &ipx_proto, kern);
	if (!sk)
		goto out;

	sk_refcnt_debug_inc(sk);
	sock_init_data(sock, sk);
	sk->sk_no_check_tx = 1;		/* Checksum off by default */
	sock->ops = &ipx_dgram_ops;
	rc = 0;
out:
	return rc;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.