Re: [PATCH V2 2/2] virtio-balloon: correct used length

[David Hildenbrand]

On 29.11.21 04:08, Jason Wang wrote:
> Spec said:
> 
> "and len the total of bytes written into the buffer."
> 
> For inflateq, deflateq and statsq, we don't process in_sg so the used
> length should be zero. For free_page_vq, tough the pages could be

s/tough/though/

> changed by the device (in the destination), spec said:
> 
> "Note: len is particularly useful for drivers using untrusted buffers:
> if a driver does not know exactly how much has been written by the
> device, the driver would have to zero the buffer in advance to ensure
> no data leakage occurs."
> 
> So 0 should be used as well here.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> Changes since V1:
> - use 0 as used length for free_page_vq
> ---
>  hw/virtio/virtio-balloon.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index 17de2558cb..9a4f491b54 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -231,7 +231,7 @@ static void balloon_stats_poll_cb(void *opaque)
>          return;
>      }
>  
> -    virtqueue_push(s->svq, s->stats_vq_elem, s->stats_vq_offset);
> +    virtqueue_push(s->svq, s->stats_vq_elem, 0);
>      virtio_notify(vdev, s->svq);
>      g_free(s->stats_vq_elem);
>      s->stats_vq_elem = NULL;
> @@ -438,7 +438,7 @@ static void virtio_balloon_handle_output(VirtIODevice 
> *vdev, VirtQueue *vq)
>              memory_region_unref(section.mr);
>          }
>  
> -        virtqueue_push(vq, elem, offset);
> +        virtqueue_push(vq, elem, 0);
>          virtio_notify(vdev, vq);
>          g_free(elem);
>          virtio_balloon_pbp_free(&pbp);
> @@ -552,7 +552,7 @@ static bool get_free_page_hints(VirtIOBalloon *dev)
>      }
>  
>  out:
> -    virtqueue_push(vq, elem, 1);
> +    virtqueue_push(vq, elem, 0);
>      g_free(elem);
>      return ret;
>  }
> 

Reviewed-by: David Hildenbrand <david@redhat.com>


-- 
Thanks,

David / dhildenb