Bluetooth: ISO: Fix not handling shutdown condition

In order to properly handle shutdown syscall the code shall not assume
that the how argument is always SHUT_RDWR resulting in SHUTDOWN_MASK as
that would result in poll to immediately report EPOLLHUP instead of
properly waiting for disconnect_cfm (Disconnect Complete) which is
rather important for the likes of BAP as the CIG may need to be
reprogrammed.

Fixes: ccf74f23 ("Bluetooth: Add BTPROTO_ISO socket type")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

net/bluetooth/iso.c

@@ -1309,7 +1309,7 @@ static int iso_sock_shutdown(struct socket *sock, int how)
 	struct sock *sk = sock->sk;
 	int err = 0;
 
-	BT_DBG("sock %p, sk %p", sock, sk);
+	BT_DBG("sock %p, sk %p, how %d", sock, sk, how);
 
 	if (!sk)
 		return 0;
@@ -1317,17 +1317,32 @@ static int iso_sock_shutdown(struct socket *sock, int how)
 	sock_hold(sk);
 	lock_sock(sk);
 
-	if (!sk->sk_shutdown) {
-		sk->sk_shutdown = SHUTDOWN_MASK;
+	switch (how) {
+	case SHUT_RD:
+		if (sk->sk_shutdown & RCV_SHUTDOWN)
+			goto unlock;
+		sk->sk_shutdown |= RCV_SHUTDOWN;
+		break;
+	case SHUT_WR:
+		if (sk->sk_shutdown & SEND_SHUTDOWN)
+			goto unlock;
+		sk->sk_shutdown |= SEND_SHUTDOWN;
+		break;
+	case SHUT_RDWR:
+		if (sk->sk_shutdown & SHUTDOWN_MASK)
+			goto unlock;
+		sk->sk_shutdown |= SHUTDOWN_MASK;
+		break;
+	}
+
 	iso_sock_clear_timer(sk);
 	__iso_sock_close(sk);
 
 	if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime &&
 	    !(current->flags & PF_EXITING))
-			err = bt_sock_wait_state(sk, BT_CLOSED,
-						 sk->sk_lingertime);
-	}
+		err = bt_sock_wait_state(sk, BT_CLOSED, sk->sk_lingertime);
 
+unlock:
 	release_sock(sk);
 	sock_put(sk);