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Message-Id: <20230131034337.55445-1-hengqi@linux.alibaba.com>
Date: Tue, 31 Jan 2023 11:43:37 +0800
From: Heng Qi <hengqi@...ux.alibaba.com>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: Jason Wang <jasowang@...hat.com>,
"Michael S . Tsirkin" <mst@...hat.com>,
Paolo Abeni <pabeni@...hat.com>,
Jakub Kicinski <kuba@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
"David S . Miller" <davem@...emloft.net>,
Daniel Borkmann <daniel@...earbox.net>,
Alexei Starovoitov <ast@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Subject: [PATCH net-next] virtio-net: fix possible unsigned integer overflow
When the single-buffer xdp is loaded and after xdp_linearize_page()
is called, *num_buf becomes 0 and (*num_buf - 1) may overflow into
a large integer in virtnet_build_xdp_buff_mrg(), resulting in
unexpected packet dropping.
Fixes: ef75cb51f139 ("virtio-net: build xdp_buff with multi buffers")
Signed-off-by: Heng Qi <hengqi@...ux.alibaba.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
---
drivers/net/virtio_net.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index aaa6fe9b214a..a8e9462903fa 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1007,6 +1007,9 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
xdp_prepare_buff(xdp, buf - VIRTIO_XDP_HEADROOM,
VIRTIO_XDP_HEADROOM + vi->hdr_len, len - vi->hdr_len, true);
+ if (!*num_buf)
+ return 0;
+
if (*num_buf > 1) {
/* If we want to build multi-buffer xdp, we need
* to specify that the flags of xdp_buff have the
@@ -1020,10 +1023,10 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
shinfo->xdp_frags_size = 0;
}
- if ((*num_buf - 1) > MAX_SKB_FRAGS)
+ if (*num_buf > MAX_SKB_FRAGS + 1)
return -EINVAL;
- while ((--*num_buf) >= 1) {
+ while (--*num_buf) {
buf = virtqueue_get_buf_ctx(rq->vq, &len, &ctx);
if (unlikely(!buf)) {
pr_debug("%s: rx error: %d buffers out of %d missing\n",
--
2.19.1.6.gb485710b
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