? 2021/5/25 ??4:45, Yongji Xie ??:> On Tue, May 25, 2021 at 2:30 PM Jason Wang <jasowang at redhat.com>
wrote:
>>
>> ? 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?
>>
> We did len -= vi->hdr_len before.
Right.
>
>>> +
>>> 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?
> Do we still need that in non-XDP cases?
I meant we check once for both XDP and non-XDP if we do it before if
(xdp_prog)
>
>> And do we need similar check in receive_big()?
>>
> It seems that the check in page_to_skb() can do similar things.
Right.
Thanks
>
> Thanks,
> Yongji
>