bpf, net: Use DEV_STAT_INC()

syzbot/KCSAN reported that races happen when multiple CPUs updating
dev->stats.tx_error concurrently. Adopt SMP safe DEV_STATS_INC() to
update the dev->stats fields.

Reported-by: syzbot <[email protected]>
Signed-off-by: yunshui <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

diff --git a/net/core/filter.c b/net/core/filter.c
index c6edfe9f41bcc308e94fae09ce9a725d334b2758..7c46ecba3b01b07dfe0d0618697a5129797a7e3a 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2274,12 +2274,12 @@ static int __bpf_redirect_neigh_v6(struct sk_buff *skb, struct net_device *dev,
 
        err = bpf_out_neigh_v6(net, skb, dev, nh);
        if (unlikely(net_xmit_eval(err)))
-               dev->stats.tx_errors++;
+               DEV_STATS_INC(dev, tx_errors);
        else
                ret = NET_XMIT_SUCCESS;
        goto out_xmit;
 out_drop:
-       dev->stats.tx_errors++;
+       DEV_STATS_INC(dev, tx_errors);
        kfree_skb(skb);
 out_xmit:
        return ret;
@@ -2380,12 +2380,12 @@ static int __bpf_redirect_neigh_v4(struct sk_buff *skb, struct net_device *dev,
 
        err = bpf_out_neigh_v4(net, skb, dev, nh);
        if (unlikely(net_xmit_eval(err)))
-               dev->stats.tx_errors++;
+               DEV_STATS_INC(dev, tx_errors);
        else
                ret = NET_XMIT_SUCCESS;
        goto out_xmit;
 out_drop:
-       dev->stats.tx_errors++;
+       DEV_STATS_INC(dev, tx_errors);
        kfree_skb(skb);
 out_xmit:
        return ret;