 void ip4_datagram_release_cb(struct sock *sk)
 {
 	const struct inet_sock *inet = inet_sk(sk);
 	const struct ip_options_rcu *inet_opt;
 	__be32 daddr = inet->inet_daddr;
	struct dst_entry *dst;
 	struct flowi4 fl4;
 	struct rtable *rt;
 
 	rcu_read_lock();

	dst = __sk_dst_get(sk);
	if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
		rcu_read_unlock();
		return;
	}
 	inet_opt = rcu_dereference(inet->inet_opt);
 	if (inet_opt && inet_opt->opt.srr)
 		daddr = inet_opt->opt.faddr;
 	rt = ip_route_output_ports(sock_net(sk), &fl4, sk, daddr,
 				   inet->inet_saddr, inet->inet_dport,
 				   inet->inet_sport, sk->sk_protocol,
 				   RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);

	dst = !IS_ERR(rt) ? &rt->dst : NULL;
	sk_dst_set(sk, dst);

 	rcu_read_unlock();
 }

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.