Re: [PATCH net 4/7] virtio_net: Fix out of bounds access of sq

[Jason Wang <jasowang@redhat.com>]

On 2019/1/17 下午7:20, Toshiaki Makita wrote:
> When XDP is disabled, curr_queue_pairs + smp_processor_id() can be
> larger than max_queue_pairs.
> There is no guarantee that we have enough XDP send queues dedicated for
> each cpu when XDP is disabled, so do not count drops on sq in that case.
>
> Fixes: 5b8f3c8d30a6 ("virtio_net: Add XDP related stats")
> Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
> ---
>   drivers/net/virtio_net.c | 17 +++++++----------
>   1 file changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 670cc15..204eedf 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -491,20 +491,17 @@ static int virtnet_xdp_xmit(struct net_device *dev,
>   	int ret, err;
>   	int i;
>   
> -	sq = virtnet_xdp_sq(vi);
> -
> -	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) {
> -		ret = -EINVAL;
> -		drops = n;
> -		goto out;
> -	}
> -
>   	/* Only allow ndo_xdp_xmit if XDP is loaded on dev, as this
>   	 * indicate XDP resources have been successfully allocated.
>   	 */
>   	xdp_prog = rcu_dereference(rq->xdp_prog);
> -	if (!xdp_prog) {
> -		ret = -ENXIO;
> +	if (!xdp_prog)
> +		return -ENXIO;
> +
> +	sq = virtnet_xdp_sq(vi);
> +
> +	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) {
> +		ret = -EINVAL;
>   		drops = n;
>   		goto out;
>   	}


Acked-by: Jason Wang <jasowang@redhat.com>