Re: [Qemu-devel] [RFC 4/4] virtio-net: Add MTU feature support

[Paolo Bonzini]

On 06/09/2016 18:11, Maxime Coquelin wrote:
>      VirtIONet *n = VIRTIO_NET(vdev);
>      struct virtio_net_config netcfg;
>  
> +    if (virtio_vdev_has_feature(vdev, VIRTIO_NET_F_MTU)) {
> +        virtio_stw_p(vdev, &netcfg.mtu, n->mtu);
> +    }

This write needs to be unconditional, otherwise you are leaking a few
bytes of QEMU's stack (corresponding to netcfg.mtu) to the guest.

Paolo

>      virtio_stw_p(vdev, &netcfg.status, n->status);
>      virtio_stw_p(vdev, &netcfg.max_virtqueue_pairs, n->max_queues);
>      memcpy(netcfg.mac, n->mac, ETH_ALEN);