tls: check RCV_SHUTDOWN in tls_wait_data

The current code does not check sk->sk_shutdown & RCV_SHUTDOWN.
tls_sw_recvmsg may return a positive value in the case where bytes have
already been copied when the socket is shutdown. sk->sk_err has been
cleared, causing the tls_wait_data to hang forever on a subsequent
invocation. Checking sk->sk_shutdown & RCV_SHUTDOWN, as in tcp_recvmsg,
fixes this problem.

Fixes: c46234eb ("tls: RX path for ktls")
Acked-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tls/tls_sw.c

@@ -646,6 +646,9 @@ static struct sk_buff *tls_wait_data(struct sock *sk, int flags,
 			return NULL;
 		}
 
+		if (sk->sk_shutdown & RCV_SHUTDOWN)
+			return NULL;
+
 		if (sock_flag(sk, SOCK_DONE))
 			return NULL;