net/llc: make opt unsigned in llc_ui_setsockopt()

The members of struct llc_sock are unsigned so if we pass a negative
value for "opt" it can cause a sign bug.  Also it can cause an integer
overflow when we multiply "opt * HZ".

CC: stable@kernel.org
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/llc/af_llc.c

@@ -1024,7 +1024,8 @@ static int llc_ui_setsockopt(struct socket *sock, int level, int optname,
 {
 	struct sock *sk = sock->sk;
 	struct llc_sock *llc = llc_sk(sk);
-	int rc = -EINVAL, opt;
+	unsigned int opt;
+	int rc = -EINVAL;
 
 	lock_sock(sk);
 	if (unlikely(level != SOL_LLC || optlen != sizeof(int)))