Subject: Re: [PATCH net] virtio-net: drop NETIF_F_FRAGLIST

From: Sergei Shtylyov <[email-masked]>
Date: Tue, 4 Aug 2015 14:11:00 +0300

Hello.

On 8/4/2015 12:55 PM, Jason Wang wrote:

> virtio declares support for NETIF_F_FRAGLIST, but assumes
> that there are at most MAX_SKB_FRAGS + 2 fragments which isn't
> always true with a fraglist.

> A longer fraglist in the skb will make the call to skb_to_sgvec overflow
> the sg array, leading to memory corruption.

> Drop NETIF_F_FRAGLIST so we only get what we can handle.

> Cc: Michael S. Tsirkin <[email-masked]>
> Signed-off-by: Jason Wang <[email-masked]>
> ---
> The patch is needed for stable.
> ---
>   drivers/net/virtio_net.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)

> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7fbca37..2347a73 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1756,9 +1756,9 @@ static int virtnet_probe(struct virtio_device *vdev)
>   	/* Do we support "hardware" checksums? */
>   	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
>   		/* This opens up the world of extra features. */
> -		dev->hw_features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
> +		dev->hw_features |= NETIF_F_HW_CSUM|NETIF_F_SG;
>   		if (csum)
> -			dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
> +			dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG;

    I'd have added spaces around | to match the style seen below.

>   		if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
>   			dev->hw_features |= NETIF_F_TSO | NETIF_F_UFO

MBR, Sergei