netdev - Re: [PATCH net-next 1/5] virtio_net: Fix an unsafe reference to the page chain

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Date: Fri, 26 May 2023 14:38:54 +0800
From: Jason Wang <jasowang@...hat.com>
To: Liang Chen <liangchen.linux@...il.com>
Cc: mst@...hat.com, virtualization@...ts.linux-foundation.org, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	xuanzhuo@...ux.alibaba.com, kuba@...nel.org, edumazet@...gle.com, 
	davem@...emloft.net, pabeni@...hat.com, alexander.duyck@...il.com
Subject: Re: [PATCH net-next 1/5] virtio_net: Fix an unsafe reference to the
 page chain

On Fri, May 26, 2023 at 1:46 PM Liang Chen <liangchen.linux@...il.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 to
> avoid such a problem.

If this issue happens only in the case of page_pool, it would be
better to squash it there.

Thanks

>
> Signed-off-by: Liang Chen <liangchen.linux@...il.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_info *vi,
>                         return NULL;
>
>                 page = (struct page *)page->private;
> -               if (page)
> +               if (!vi->mergeable_rx_bufs && page)
>                         give_pages(rq, page);
>                 goto ok;
>         }
> --
> 2.31.1
>