net/smc: do not schedule tx_work in SMC_CLOSED state

The setsockopts options TCP_NODELAY and TCP_CORK may schedule the
tx worker. Make sure the socket is not yet moved into SMC_CLOSED
state (for instance by a shutdown SHUT_RDWR call).

Reported-by: syzbot+92209502e7aab127c75f@syzkaller.appspotmail.com
Reported-by: syzbot+b972214bb803a343f4fe@syzkaller.appspotmail.com
Fixes: 01d2f7e2 ("net/smc: sockopts TCP_NODELAY and TCP_CORK")
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/af_smc.c

@@ -1732,14 +1732,18 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
 		}
 		break;
 	case TCP_NODELAY:
-		if (sk->sk_state != SMC_INIT && sk->sk_state != SMC_LISTEN) {
+		if (sk->sk_state != SMC_INIT &&
+		    sk->sk_state != SMC_LISTEN &&
+		    sk->sk_state != SMC_CLOSED) {
 			if (val && !smc->use_fallback)
 				mod_delayed_work(system_wq, &smc->conn.tx_work,
 						 0);
 		}
 		break;
 	case TCP_CORK:
-		if (sk->sk_state != SMC_INIT && sk->sk_state != SMC_LISTEN) {
+		if (sk->sk_state != SMC_INIT &&
+		    sk->sk_state != SMC_LISTEN &&
+		    sk->sk_state != SMC_CLOSED) {
 			if (!val && !smc->use_fallback)
 				mod_delayed_work(system_wq, &smc->conn.tx_work,
 						 0);