? 2021/5/25 ??12:58, 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>
> ---
> drivers/net/virtio_net.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index c4711e23af88..2dcdc1a3c7e8 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -668,6 +668,13 @@ static struct sk_buff *receive_small(struct net_device
*dev,
> void *orig_data;
> u32 act;
>
> + if (unlikely(len > GOOD_PACKET_LEN)) {
> + pr_debug("%s: rx error: len %u exceeds max size %lu\n",
> + dev->name, len, GOOD_PACKET_LEN);
> + dev->stats.rx_length_errors++;
> + goto err_xdp;
> + }
Need to count vi->hdr_len here?
> +
> if (unlikely(hdr->hdr.gso_type))
> goto err_xdp;
>
> @@ -739,6 +746,14 @@ static struct sk_buff *receive_small(struct net_device
*dev,
> }
> rcu_read_unlock();
>
> + if (unlikely(len > GOOD_PACKET_LEN)) {
> + pr_debug("%s: rx error: len %u exceeds max size %lu\n",
> + dev->name, len, GOOD_PACKET_LEN);
> + dev->stats.rx_length_errors++;
> + put_page(page);
> + return NULL;
> + }
> +
> skb = build_skb(buf, buflen);
> if (!skb) {
> put_page(page);
> @@ -822,6 +837,13 @@ static struct sk_buff *receive_mergeable(struct
net_device *dev,
> void *data;
> u32 act;
>
> + 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_xdp;
> + }
There's a similar check after the XDP, let's simply move it here?
And do we need similar check in receive_big()?
Thanks
> +
> /* Transient failure which in theory could occur if
> * in-flight packets from before XDP was enabled reach
> * the receive path after XDP is loaded.