This is a note to let you know that I've just added the patch titled ipv6/sit: use DEV_STATS_INC() to avoid data-races to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ipv6-sit-use-dev_stats_inc-to-avoid-data-races.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 4cfeeaba82970a622d5584e4190b829c592200a3 Author: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Tue Nov 15 08:53:56 2022 +0000 ipv6/sit: use DEV_STATS_INC() to avoid data-races [ Upstream commit cb34b7cf17ecf33499c9298943f85af247abc1e9 ] syzbot/KCSAN reported that multiple cpus are updating dev->stats.tx_error concurrently. This is because sit tunnels are NETIF_F_LLTX, meaning their ndo_start_xmit() is not protected by a spinlock. While original KCSAN report was about tx path, rx path has the same issue. Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index 5703d3cbea9b..70d81bba5093 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -694,7 +694,7 @@ static int ipip6_rcv(struct sk_buff *skb) skb->dev = tunnel->dev; if (packet_is_spoofed(skb, iph, tunnel)) { - tunnel->dev->stats.rx_errors++; + DEV_STATS_INC(tunnel->dev, rx_errors); goto out; } @@ -714,8 +714,8 @@ static int ipip6_rcv(struct sk_buff *skb) net_info_ratelimited("non-ECT from %pI4 with TOS=%#x\n", &iph->saddr, iph->tos); if (err > 1) { - ++tunnel->dev->stats.rx_frame_errors; - ++tunnel->dev->stats.rx_errors; + DEV_STATS_INC(tunnel->dev, rx_frame_errors); + DEV_STATS_INC(tunnel->dev, rx_errors); goto out; } } @@ -942,7 +942,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb, if (!rt) { rt = ip_route_output_flow(tunnel->net, &fl4, NULL); if (IS_ERR(rt)) { - dev->stats.tx_carrier_errors++; + DEV_STATS_INC(dev, tx_carrier_errors); goto tx_error_icmp; } dst_cache_set_ip4(&tunnel->dst_cache, &rt->dst, fl4.saddr); @@ -950,14 +950,14 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb, if (rt->rt_type != RTN_UNICAST && rt->rt_type != RTN_LOCAL) { ip_rt_put(rt); - dev->stats.tx_carrier_errors++; + DEV_STATS_INC(dev, tx_carrier_errors); goto tx_error_icmp; } tdev = rt->dst.dev; if (tdev == dev) { ip_rt_put(rt); - dev->stats.collisions++; + DEV_STATS_INC(dev, collisions); goto tx_error; } @@ -970,7 +970,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb, mtu = dst_mtu(&rt->dst) - t_hlen; if (mtu < IPV4_MIN_MTU) { - dev->stats.collisions++; + DEV_STATS_INC(dev, collisions); ip_rt_put(rt); goto tx_error; } @@ -1009,7 +1009,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb, struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom); if (!new_skb) { ip_rt_put(rt); - dev->stats.tx_dropped++; + DEV_STATS_INC(dev, tx_dropped); kfree_skb(skb); return NETDEV_TX_OK; } @@ -1039,7 +1039,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb, dst_link_failure(skb); tx_error: kfree_skb(skb); - dev->stats.tx_errors++; + DEV_STATS_INC(dev, tx_errors); return NETDEV_TX_OK; } @@ -1058,7 +1058,7 @@ static netdev_tx_t sit_tunnel_xmit__(struct sk_buff *skb, return NETDEV_TX_OK; tx_error: kfree_skb(skb); - dev->stats.tx_errors++; + DEV_STATS_INC(dev, tx_errors); return NETDEV_TX_OK; } @@ -1087,7 +1087,7 @@ static netdev_tx_t sit_tunnel_xmit(struct sk_buff *skb, return NETDEV_TX_OK; tx_err: - dev->stats.tx_errors++; + DEV_STATS_INC(dev, tx_errors); kfree_skb(skb); return NETDEV_TX_OK;