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From: Maxime Coquelin <maxime.coquelin@redhat.com>
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Date: Fri, 16 Sep 2016 08:36:02 +0200
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Subject: Re: [Qemu-devel] [RFC 4/4] virtio-net: Add MTU feature support
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To: Paolo Bonzini <pbonzini@redhat.com>, mst@redhat.com, qemu-devel@nongnu.org
Cc: jasowang@redhat.com, Aaron Conole <aconole@redhat.com>



On 09/16/2016 12:16 AM, Paolo Bonzini wrote:
>
>
> 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.

Right, thanks for pointing this out. I'll make it unconditional.

Maxime

> 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);