virtio_vdpa: reject invalid vq indices

Do not call vDPA drivers' callbacks with vq indicies larger than what
the drivers indicate that they support.  vDPA drivers do not bounds
check the indices.
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Link: https://lore.kernel.org/r/20210701114652.21956-1-vincent.whitchurch@axis.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

drivers/virtio/virtio_vdpa.c

@@ -151,6 +151,9 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
 	if (!name)
 		return NULL;
 
+	if (index >= vdpa->nvqs)
+		return ERR_PTR(-ENOENT);
+
 	/* Queue shouldn't already be set up. */
 	if (ops->get_vq_ready(vdpa, index))
 		return ERR_PTR(-ENOENT);