On Wed, Oct 05, 2011 at 03:50:14PM +0200, Sasha Levin wrote:
> On Mon, 2011-10-03 at 20:40 +0200, Michael S. Tsirkin wrote:
> > On Wed, Sep 28, 2011 at 05:40:55PM +0300, Sasha Levin wrote:
> > > This patch prevents a NULL dereference when the user has passed a length
> > > longer than an actual buffer to virtio-net.
> > >
> > > Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> > > Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
> > > Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > > Cc: netdev@xxxxxxxxxxxxxxx
> > > Cc: kvm@xxxxxxxxxxxxxxx
> > > Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
> > > ---
> > > drivers/net/virtio_net.c | 12 +++++++++++-
> > > 1 files changed, 11 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > index bde0dec..4a53d2a 100644
> > > --- a/drivers/net/virtio_net.c
> > > +++ b/drivers/net/virtio_net.c
> > > @@ -208,12 +208,22 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
> > > return NULL;
> > > }
> > >
> > > - while (len) {
> > > + while (len && page) {
> > > set_skb_frag(skb, page, offset, &len);
> > > page = (struct page *)page->private;
> > > offset = 0;
> > > }
> > >
> > > + /*
> > > + * This is the case where we ran out of pages in our linked list, but
> > > + * supposedly have more data to read.
> >
> > Again, let's clarify that this only happens with broken devices.
>
> I think that the code within the if() makes it clear that it isn't the
> regular path.
It doesn't make it clear that this never happens in absence of bugs.
> --
>
> Sasha.
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