netdev - RE: [PATCH net] virtio_net: check virtqueue_add

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Date:   Tue, 6 Jul 2021 03:16:33 +0000
From:   wangyunjian <wangyunjian@...wei.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
CC:     "kuba@...nel.org" <kuba@...nel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        dingxiaoxiong <dingxiaoxiong@...wei.com>
Subject: RE: [PATCH net] virtio_net: check virtqueue_add_sgs() return value

> -----Original Message-----
> From: Michael S. Tsirkin [mailto:mst@...hat.com]
> Sent: Tuesday, July 6, 2021 2:08 AM
> To: wangyunjian <wangyunjian@...wei.com>
> Cc: kuba@...nel.org; davem@...emloft.net; netdev@...r.kernel.org;
> jasowang@...hat.com; dingxiaoxiong <dingxiaoxiong@...wei.com>
> Subject: Re: [PATCH net] virtio_net: check virtqueue_add_sgs() return value
> 
> On Mon, Jul 05, 2021 at 09:53:39PM +0800, wangyunjian wrote:
> > From: Yunjian Wang <wangyunjian@...wei.com>
> >
> > As virtqueue_add_sgs() can fail, we should check the return value.
> >
> > Addresses-Coverity-ID: 1464439 ("Unchecked return value")
> > Fixes: a7c58146cf9a ("virtio_net: don't crash if virtqueue is
> > broken.")
> 
> What does this have to do with it?

It's this commit that removes the check.
So delete this fix tag?

> 
> > Signed-off-by: Yunjian Wang <wangyunjian@...wei.com>
> > ---
> >  drivers/net/virtio_net.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index
> > b0b81458ca94..2b852578551e 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -1743,6 +1743,7 @@ static bool virtnet_send_command(struct
> > virtnet_info *vi, u8 class, u8 cmd,  {
> >  	struct scatterlist *sgs[4], hdr, stat;
> >  	unsigned out_num = 0, tmp;
> > +	int ret;
> >
> >  	/* Caller should know better */
> >  	BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ)); @@
> > -1762,7 +1763,9 @@ static bool virtnet_send_command(struct virtnet_info
> *vi, u8 class, u8 cmd,
> >  	sgs[out_num] = &stat;
> >
> >  	BUG_ON(out_num + 1 > ARRAY_SIZE(sgs));
> > -	virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC);
> > +	ret = virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC);
> > +	if (ret < 0)
> > +		return false;
> 
> and maybe dev_warn here. these things should not happen.

OK, I will add it in next version.

Thanks
Yunjian

> 
> 
> >
> >  	if (unlikely(!virtqueue_kick(vi->cvq)))
> >  		return vi->ctrl->status == VIRTIO_NET_OK;
> > --
> > 2.23.0