bpf, vsock: Fix poll() missing a queue

BugLink: https://bugs.launchpad.net/bugs/2102118

[ Upstream commit 9f0fc98145218ff8f50d8cfa3b393785056c53e1 ]

When a verdict program simply passes a packet without redirection, sk_msg
is enqueued on sk_psock::ingress_msg. Add a missing check to poll().

Fixes: 634f1a7110 ("vsock: support sockmap")
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Luigi Leonardi <leonardi@redhat.com>
Link: https://lore.kernel.org/r/20241118-vsock-bpf-poll-close-v1-1-f1b9669cacdc@rbox.co
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

net/vmw_vsock/af_vsock.c

@@ -1063,6 +1063,9 @@ static __poll_t vsock_poll(struct file *file, struct socket *sock,
 		mask |= EPOLLRDHUP;
 	}
 
+	if (sk_is_readable(sk))
+		mask |= EPOLLIN | EPOLLRDNORM;
+
 	if (sock->type == SOCK_DGRAM) {
 		/* For datagram sockets we can read if there is something in
 		 * the queue and write as long as the socket isn't shutdown for