net/smc: no shutdown in state SMC_LISTEN

Invoking shutdown for a socket in state SMC_LISTEN does not make
sense. Nevertheless programs like syzbot fuzzing the kernel may
try to do this. For SMC this means a socket refcounting problem.
This patch makes sure a shutdown call for an SMC socket in state
SMC_LISTEN simply returns with -ENOTCONN.
Signed-off-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/smc/af_smc.c

@@ -1397,8 +1397,7 @@ static int smc_shutdown(struct socket *sock, int how)
 	lock_sock(sk);
 
 	rc = -ENOTCONN;
-	if ((sk->sk_state != SMC_LISTEN) &&
-	    (sk->sk_state != SMC_ACTIVE) &&
+	if ((sk->sk_state != SMC_ACTIVE) &&
 	    (sk->sk_state != SMC_PEERCLOSEWAIT1) &&
 	    (sk->sk_state != SMC_PEERCLOSEWAIT2) &&
 	    (sk->sk_state != SMC_APPCLOSEWAIT1) &&