Messages in this thread | | | From | Yongji Xie <> | Date | Mon, 31 May 2021 16:23:59 +0800 | Subject | Re: Re: [PATCH v3] virtio-net: Add validation for used length |
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On Mon, May 31, 2021 at 3:51 PM Jason Wang <jasowang@redhat.com> wrote: > > > 在 2021/5/31 下午3:19, Yongji Xie 写道: > > On Mon, May 31, 2021 at 2:49 PM Jason Wang <jasowang@redhat.com> wrote: > >> > >> 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. > >> > > If so, we will miss the statistics of xdp_drops. Is it OK? > > > It should be ok, we still had drops and it was dropped before dealing > with XDP. > > The motivation is to have simple codes. >
OK, will send v4 soon.
Thanks, Yongji
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