? 2021/5/31 ??9:58, Xie Yongji ??:> This adds validation for used length (might come
> from an untrusted device) to avoid data corruption
> or loss.
>
> Signed-off-by: Xie Yongji <xieyongji at bytedance.com>
Acked-by: Jason Wang <jasowang at redhat.com>
> ---
> drivers/net/virtio_net.c | 20 +++++++++++++-------
> 1 file changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 073fec4c0df1..ed969b65126e 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -730,6 +730,12 @@ static struct sk_buff *receive_small(struct net_device
*dev,
> len -= vi->hdr_len;
> stats->bytes += len;
>
> + if (unlikely(len > GOOD_PACKET_LEN)) {
> + pr_debug("%s: rx error: len %u exceeds max size %d\n",
> + dev->name, len, GOOD_PACKET_LEN);
> + dev->stats.rx_length_errors++;
> + goto err_len;
> + }
> rcu_read_lock();
> xdp_prog = rcu_dereference(rq->xdp_prog);
> if (xdp_prog) {
> @@ -833,6 +839,7 @@ static struct sk_buff *receive_small(struct net_device
*dev,
> err_xdp:
> rcu_read_unlock();
> stats->xdp_drops++;
> +err_len:
> stats->drops++;
> put_page(page);
> xdp_xmit:
> @@ -886,6 +893,12 @@ static struct sk_buff *receive_mergeable(struct
net_device *dev,
> head_skb = NULL;
> stats->bytes += len - vi->hdr_len;
>
> + if (unlikely(len > truesize)) {
> + pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
> + dev->name, len, (unsigned long)ctx);
> + dev->stats.rx_length_errors++;
> + goto err_skb;
> + }
> rcu_read_lock();
> xdp_prog = rcu_dereference(rq->xdp_prog);
> if (xdp_prog) {
> @@ -1012,13 +1025,6 @@ static struct sk_buff *receive_mergeable(struct
net_device *dev,
> }
> rcu_read_unlock();
>
> - if (unlikely(len > truesize)) {
> - pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
> - dev->name, len, (unsigned long)ctx);
> - dev->stats.rx_length_errors++;
> - goto err_skb;
> - }
> -
> head_skb = page_to_skb(vi, rq, page, offset, len, truesize, !xdp_prog,
> metasize, !!headroom);
> curr_skb = head_skb;