Messages in this thread | | | Subject | Re: [PATCH v3] virtio-net: Add validation for used length | From | Jason Wang <> | Date | Mon, 31 May 2021 14:49:07 +0800 |
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在 2021/5/28 下午8:11, Xie Yongji 写道: > This adds validation for used length (might come > from an untrusted device) to avoid data corruption > or loss. > > Signed-off-by: Xie Yongji <xieyongji@bytedance.com> > --- > drivers/net/virtio_net.c | 28 +++++++++++++++++++++------- > 1 file changed, 21 insertions(+), 7 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 073fec4c0df1..01f15b65824c 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -732,6 +732,17 @@ static struct sk_buff *receive_small(struct net_device *dev, > > rcu_read_lock(); > xdp_prog = rcu_dereference(rq->xdp_prog); > + 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++; > + if (xdp_prog) > + goto err_xdp; > + > + rcu_read_unlock(); > + put_page(page); > + return NULL; > + } > if (xdp_prog) { > struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset; > struct xdp_frame *xdpf; > @@ -888,6 +899,16 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > > rcu_read_lock(); > xdp_prog = rcu_dereference(rq->xdp_prog); > + 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++; > + if (xdp_prog) > + goto err_xdp; > + > + rcu_read_unlock(); > + goto err_skb; > + }
Patch looks correct but I'd rather not bother XDP here. It would be better if we just do the check before rcu_read_lock() and use err_skb directly() to avoid RCU/XDP stuffs.
Thanks
> if (xdp_prog) { > struct xdp_frame *xdpf; > struct page *xdp_page; > @@ -1012,13 +1033,6 @@ 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;
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