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Date: Thu, 27 Nov 2014 18:40:30 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [2.2 PATCH V2] virtio-net: fix unmap leak
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Fam Zheng <famz@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Jason Wang <jasowang@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>, qemu-stable <qemu-stable@nongnu.org>, Anthony Liguori <aliguori@amazon.com>

On Thu, Nov 27, 2014 at 02:09:06PM +0000, Peter Maydell wrote:
> On 27 November 2014 at 12:42, Peter Maydell <peter.maydell@linaro.org> wrote:
> > On 27 November 2014 at 12:33, Michael S. Tsirkin <mst@redhat.com> wrote:
> >> 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?
> >
> > I can pick it up. I was waiting a bit to check that everybody
> > was happy that this is the correct way to fix the bug and the
> > patch is ok...
> 
> ...but discussing this with Stefan H on IRC we realised that the same
> issue also (at least potentially) affects virtio-blk, which suggests
> that we should fix this by making the core virtio code cope with
> backends which modify the sglists.
> 
> -- PMM

I just sent a minimal fix for virtio blk.
This way core rework can wait for 2.3.

-- 
MST