Re: [PATCH] virtio-net: check the existence of peer before accesing its config

[Cornelia Huck]

On Mon, 27 Jul 2020 05:41:17 -0400
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Mon, Jul 27, 2020 at 03:43:28PM +0800, Jason Wang wrote:
> > We try to get config from peer unconditionally which may lead NULL
> > pointer dereference. Add a check before trying to access the config.
> > 
> > Fixes: 108a64818e69b ("vhost-vdpa: introduce vhost-vdpa backend")
> > Cc: Cindy Lu <lulu@redhat.com>
> > Tested-by: Cornelia Huck <cohuck@redhat.com>
> > Signed-off-by: Jason Wang <jasowang@redhat.com>  
> 
> I am a bit lost here. Isn't this invoked
> when guest attempts to read the config?
> With no peer, what do we return to guest?

Same as with a non-vdpa peer? It's the dereference that needs to be
guarded.

> A code comment might be helpful here.
> 
> > ---
> >  hw/net/virtio-net.c | 22 +++++++++++-----------
> >  1 file changed, 11 insertions(+), 11 deletions(-)