Re: [Qemu-devel] [2.2 PATCH V2] virtio-net: fix unmap leak

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Nov 27, 2014 at 06:04:03PM +0800, Jason Wang wrote:
> virtio_net_handle_ctrl() and other functions that process control vq
> request call iov_discard_front() which will shorten the iov. This will
> lead unmapping in virtqueue_push() leaks mapping.
> 
> Fixes this by keeping the original iov untouched and using a temp variable
> in those functions.
> 
> Cc: Wen Congyang <wency@cn.fujitsu.com>
> Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Peter, can you pick this up or do you want a pull request?

> ---
> Changes from V1:
> - Use g_memdup() to simplify codes
> ---
>  hw/net/virtio-net.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 9b88775..e574bd4 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -798,7 +798,7 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
>      virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
>      VirtQueueElement elem;
>      size_t s;
> -    struct iovec *iov;
> +    struct iovec *iov, *iov2;
>      unsigned int iov_cnt;
>  
>      while (virtqueue_pop(vq, &elem)) {
> @@ -808,8 +808,8 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
>              exit(1);
>          }
>  
> -        iov = elem.out_sg;
>          iov_cnt = elem.out_num;
> +        iov2 = iov = g_memdup(elem.out_sg, sizeof(struct iovec) * elem.out_num);
>          s = iov_to_buf(iov, iov_cnt, 0, &ctrl, sizeof(ctrl));
>          iov_discard_front(&iov, &iov_cnt, sizeof(ctrl));
>          if (s != sizeof(ctrl)) {
> @@ -833,6 +833,7 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
>  
>          virtqueue_push(vq, &elem, sizeof(status));
>          virtio_notify(vdev, vq);
> +        g_free(iov2);
>      }
>  }
>  
> -- 
> 1.9.1