int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
		   unsigned int optlen)
{
	const struct inet_connection_sock *icsk = inet_csk(sk);

	if (level != SOL_TCP)
		return icsk->icsk_af_ops->setsockopt(sk, level, optname,
						     optval, optlen);
	return do_tcp_setsockopt(sk, level, optname, optval, optlen);
}

The product divides a value by zero.