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From:   Liang Chen <liangchen.linux@gmail.com>
Date:   Sat, 27 May 2023 20:33:30 +0800
Message-ID: <CAKhg4tKGnXh32a8M1V-r7sP8uCSnyMYhoFXZTv3ixJOcJ1mWOg@mail.gmail.com>
Subject: Re: [PATCH net-next 1/5] virtio_net: Fix an unsafe reference to the
 page chain
To:     Jason Wang <jasowang@redhat.com>
Cc:     mst@redhat.com, virtualization@lists.linux-foundation.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        xuanzhuo@linux.alibaba.com, kuba@kernel.org, edumazet@google.com,
        davem@davemloft.net, pabeni@redhat.com, alexander.duyck@gmail.com
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On Fri, May 26, 2023 at 2:39=E2=80=AFPM Jason Wang <jasowang@redhat.com> wr=
ote:
>
> On Fri, May 26, 2023 at 1:46=E2=80=AFPM Liang Chen <liangchen.linux@gmail=
.com> wrote:
> >
> > "private" of buffer page is currently used for big mode to chain pages.
> > But in mergeable mode, that offset of page could mean something else,
> > e.g. when page_pool page is used instead. So excluding mergeable mode t=
o
> > avoid such a problem.
>
> If this issue happens only in the case of page_pool, it would be
> better to squash it there.
>
> Thanks

Sure, thanks!


>
> >
> > Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
> > ---
> >  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 5a7f7a76b920..c5dca0d92e64 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -497,7 +497,7 @@ static struct sk_buff *page_to_skb(struct virtnet_i=
nfo *vi,
> >                         return NULL;
> >
> >                 page =3D (struct page *)page->private;
> > -               if (page)
> > +               if (!vi->mergeable_rx_bufs && page)
> >                         give_pages(rq, page);
> >                 goto ok;
> >         }
> > --
> > 2.31.1
> >
>