linux-kernel - Re: [PATCH net] virtio_net: fix return value check in receive

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Message-ID: <b654b4f3-6b75-c7ae-8d20-f60835c5c1b0@redhat.com>
Date:   Mon, 4 Dec 2017 15:10:28 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     wangyunjian <wangyunjian@...wei.com>, linux-kernel@...r.kernel.org
Cc:     mst@...hat.com, caihe@...wei.com
Subject: Re: [PATCH net] virtio_net: fix return value check in
 receive_mergeable()



On 2017年12月04日 14:02, wangyunjian wrote:
> From: Yunjian Wang <wangyunjian@...wei.com>
>
> 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@...wei.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 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?

Thanks