vsock: fix possible infinite sleep in vsock_connectible_wait_data()

Bugzilla: https://bugzilla.redhat.com/2160028

commit 466a853
Author: Dexuan Cui <decui@microsoft.com>
Date:   Mon Oct 31 19:17:06 2022 -0700

    vsock: fix possible infinite sleep in vsock_connectible_wait_data()

    Currently vsock_connectible_has_data() may miss a wakeup operation
    between vsock_connectible_has_data() == 0 and the prepare_to_wait().

    Fix the race by adding the process to the wait queue before checking
    vsock_connectible_has_data().

    Fixes: b3f7fd5 ("af_vsock: separate wait data loop")
    Signed-off-by: Dexuan Cui <decui@microsoft.com>
    Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
    Reported-by: Frédéric Dalleau <frederic.dalleau@docker.com>
    Tested-by: Frédéric Dalleau <frederic.dalleau@docker.com>
    Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>

Author: stefano-garzarella

net/vmw_vsock/af_vsock.c

@@ -1905,8 +1905,11 @@ static int vsock_connectible_wait_data(struct sock *sk,
 	err = 0;
 	transport = vsk->transport;
 
-	while ((data = vsock_connectible_has_data(vsk)) == 0) {
+	while (1) {
 		prepare_to_wait(sk_sleep(sk), wait, TASK_INTERRUPTIBLE);
+		data = vsock_connectible_has_data(vsk);
+		if (data != 0)
+			break;
 
 		if (sk->sk_err != 0 ||
 		    (sk->sk_shutdown & RCV_SHUTDOWN) ||