Commit ca9e83b4 authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
Browse files

virtio-net: correctly update XDP_TX counters 



Commit 5b8f3c8d ("virtio_net: Add XDP related stats") tries to
count TX XDP stats in virtnet_receive(). This will cause several
issues:

- virtnet_xdp_sq() was called without checking whether or not XDP is
  set. This may cause out of bound access when there's no enough txq
  for XDP.
- Stats were updated even if there's no XDP/XDP_TX.

Fixing this by reusing virtnet_xdp_xmit() for XDP_TX which can counts
TX XDP counter itself and remove the unnecessary tx stats embedded in
rx stats.

Reported-by: default avatar <syzbot+604f8271211546f5b3c7@syzkaller.appspotmail.com>
Fixes: 5b8f3c8d ("virtio_net: Add XDP related stats")
Cc: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6293e4d6

drivers/net/virtio_net.c

+4 −35
Original line number Diff line number Diff line
@@ -105,10 +105,6 @@ struct virtnet_rq_stats { 


struct virtnet_rx_stats {

	struct virtnet_rq_stat_items rx;

	struct {

		unsigned int xdp_tx;

		unsigned int xdp_tx_drops;

	} tx;

};



#define VIRTNET_SQ_STAT(m)	offsetof(struct virtnet_sq_stats, m)
@@ -485,22 +481,6 @@ static struct send_queue *virtnet_xdp_sq(struct virtnet_info *vi) 
	return &vi->sq[qp];

}



static int __virtnet_xdp_tx_xmit(struct virtnet_info *vi,

				   struct xdp_frame *xdpf)

{

	struct xdp_frame *xdpf_sent;

	struct send_queue *sq;

	unsigned int len;



	sq = virtnet_xdp_sq(vi);



	/* Free up any pending old buffers before queueing new ones. */

	while ((xdpf_sent = virtqueue_get_buf(sq->vq, &len)) != NULL)

		xdp_return_frame(xdpf_sent);



	return __virtnet_xdp_xmit_one(vi, sq, xdpf);

}



static int virtnet_xdp_xmit(struct net_device *dev,

			    int n, struct xdp_frame **frames, u32 flags)

{
@@ -707,10 +687,8 @@ static struct sk_buff *receive_small(struct net_device *dev, 
			xdpf = convert_to_xdp_frame(&xdp);

			if (unlikely(!xdpf))

				goto err_xdp;

			stats->tx.xdp_tx++;

			err = __virtnet_xdp_tx_xmit(vi, xdpf);

			if (unlikely(err)) {

				stats->tx.xdp_tx_drops++;

			err = virtnet_xdp_xmit(dev, 1, &xdpf, 0);

			if (unlikely(err < 0)) {

				trace_xdp_exception(vi->dev, xdp_prog, act);

				goto err_xdp;

			}
@@ -879,10 +857,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, 
			xdpf = convert_to_xdp_frame(&xdp);

			if (unlikely(!xdpf))

				goto err_xdp;

			stats->tx.xdp_tx++;

			err = __virtnet_xdp_tx_xmit(vi, xdpf);

			if (unlikely(err)) {

				stats->tx.xdp_tx_drops++;

			err = virtnet_xdp_xmit(dev, 1, &xdpf, 0);

			if (unlikely(err < 0)) {

				trace_xdp_exception(vi->dev, xdp_prog, act);

				if (unlikely(xdp_page != page))

					put_page(xdp_page);
@@ -1315,7 +1291,6 @@ static int virtnet_receive(struct receive_queue *rq, int budget, 
{

	struct virtnet_info *vi = rq->vq->vdev->priv;

	struct virtnet_rx_stats stats = {};

	struct send_queue *sq;

	unsigned int len;

	void *buf;

	int i;
@@ -1351,12 +1326,6 @@ static int virtnet_receive(struct receive_queue *rq, int budget, 
	}

	u64_stats_update_end(&rq->stats.syncp);



	sq = virtnet_xdp_sq(vi);

	u64_stats_update_begin(&sq->stats.syncp);

	sq->stats.xdp_tx += stats.tx.xdp_tx;

	sq->stats.xdp_tx_drops += stats.tx.xdp_tx_drops;

	u64_stats_update_end(&sq->stats.syncp);



	return stats.rx.packets;

}

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