Re: [Qemu-devel] [PATCH] virtio: validate the existence of handle_output before calling it

[Jason Wang]

On Sat, Feb 14, 2015 at 4:18 AM, Don Koch <address@hidden> wrote:
> On Thu, 12 Feb 2015 11:05:17 +0800
> Jason Wang <address@hidden> wrote:
>
> >  We don't validate the existence of handle_output which may let a 
> > buggy
> >  guest to trigger a SIGSEV easily. Fix this by validate its existence
> >  before.
> >  
> >  Cc: address@hidden
> >  Cc: Anthony Liguori <address@hidden>
> >  Cc: Michael S. Tsirkin <address@hidden>
> >  Signed-off-by: Jason Wang <address@hidden>
> >  ---
> >   hw/virtio/virtio.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> >  
> >  diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> >  index d735343..ffc22e8 100644
> >  --- a/hw/virtio/virtio.c
> >  +++ b/hw/virtio/virtio.c
> >  @@ -761,6 +761,10 @@ void virtio_queue_notify_vq(VirtQueue *vq)
> >   {
> >       if (vq->vring.desc) {
> >           VirtIODevice *vdev = vq->vdev;
> >  +
> >  +        if (!vq->handle_output) {
> >  +            return;
> >  +        }
>
> Maybe better to just change line 762 to:
>      if (vq->vring.desc && vq->handle_output) {
>
> -d

Yes, better.
> >           trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
> >           vq->handle_output(vdev, vq);
> >       }
> >  -- 
> >  1.9.1
> >  
> >