Re: [PATCH net] virtio_net: fix return value check in receive_mergeable()

[Jason Wang]

On 2017å12æ04æ 19:25, wangyunjian wrote:
> > -----Original Message-----
> > From: Jason Wang [mailto:jasowang@xxxxxxxxxx]
> > Sent: Monday, December 04, 2017 3:10 PM
> > To: wangyunjian <wangyunjian@xxxxxxxxxx>; linux-
> > kernel@xxxxxxxxxxxxxxx
> > Cc: mst@xxxxxxxxxx; caihe <caihe@xxxxxxxxxx>
> > Subject: Re: [PATCH net] virtio_net: fix return value check in
> > receive_mergeable()
> >
> >
> >
> > On 2017å12æ04æ 14:02, wangyunjian wrote:
> > > From: Yunjian Wang <wangyunjian@xxxxxxxxxx>
> > >
> > > The function virtqueue_get_buf_ctx() could return NULL, the return
> > > value 'buf' need to be checked with NULL, not value 'ctx'.
> > >
> > > Signed-off-by: Yunjian Wang <wangyunjian@xxxxxxxxxx>
> > > ---
> > >    drivers/net/virtio_net.c | 2 +-
> > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > index 19a985e..559b215 100644
> > > --- a/drivers/net/virtio_net.c
> > > +++ b/drivers/net/virtio_net.c
> > > @@ -756,7 +756,7 @@ static struct sk_buff *receive_mergeable(struct
> > net_device *dev,
> > >    		int num_skb_frags;
> > >
> > >    		buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);
> > > -		if (unlikely(!ctx)) {
> > > +		if (unlikely(!buf)) {
> > >    			pr_debug("%s: rx error: %d buffers out of %d
> > missing\n",
> > >    				 dev->name, num_buf,
> > >    				 virtio16_to_cpu(vi->vdev,
> > Hi:
> >
> > The path looks good but I'm not sure this is a real fix since we add
> > data and ctx simultaneously in virtqueue_add_inbuf_ctx().
> >
> > Any bad result you see without this patch?
> Now no problem has been found yet, and I found it when reviewing the code.
>
> Thanks

Then I think it's better to go net-next. Michael, any idea on this?

Thanks

> > Thanks