static int sctp_writeable(struct sock *sk)
{
	int amt = 0;

	amt = sk->sk_sndbuf - sk_wmem_alloc_get(sk);
	if (amt < 0)
		amt = 0;
	return amt;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.