Patch "ipv6/sit: use DEV_STATS_INC() to avoid data-races" has been added to the 6.0-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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 6.0-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-6.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 469a2dd595a06f1f06e58f903582a33ec7a20e68
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 59b2d9a6210c..ccb39b1e730f 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;