vhost/vsock: accept only packets with the right dst_cid

vhost/vsock: accept only packets with the right dst_cid

BugLink: https://bugs.launchpad.net/bugs/1860602
[ Upstream commit 8a3cc29c316c17de590e3ff8b59f3d6cbfd37b0a ]

When we receive a new packet from the guest, we check if the
src_cid is correct, but we forgot to check the dst_cid.

The host should accept only packets where dst_cid is
equal to the host CID.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>