netdev - [PATCH net] wireguard: use DEV_STATS

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Message-ID: <20231116100217.2654521-1-edumazet@google.com>
Date: Thu, 16 Nov 2023 10:02:17 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>, syzbot <syzkaller@...glegroups.com>, 
	"Jason A . Donenfeld" <Jason@...c4.com>
Subject: [PATCH net] wireguard: use DEV_STATS_INC()

wg_xmit() can be called concurrently, KCSAN reported [1]
some device stats updates can be lost.

Use DEV_STATS_INC() for this unlikely case.

[1]
BUG: KCSAN: data-race in wg_xmit / wg_xmit

read-write to 0xffff888104239160 of 8 bytes by task 1375 on cpu 0:
wg_xmit+0x60f/0x680 drivers/net/wireguard/device.c:231
__netdev_start_xmit include/linux/netdevice.h:4918 [inline]
netdev_start_xmit include/linux/netdevice.h:4932 [inline]
xmit_one net/core/dev.c:3543 [inline]
dev_hard_start_xmit+0x11b/0x3f0 net/core/dev.c:3559
...

read-write to 0xffff888104239160 of 8 bytes by task 1378 on cpu 1:
wg_xmit+0x60f/0x680 drivers/net/wireguard/device.c:231
__netdev_start_xmit include/linux/netdevice.h:4918 [inline]
netdev_start_xmit include/linux/netdevice.h:4932 [inline]
xmit_one net/core/dev.c:3543 [inline]
dev_hard_start_xmit+0x11b/0x3f0 net/core/dev.c:3559
...

Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
Reported-by: syzbot <syzkaller@...glegroups.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Jason A. Donenfeld <Jason@...c4.com>
---
 drivers/net/wireguard/device.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireguard/device.c b/drivers/net/wireguard/device.c
index 258dcc1039216f311a223fd348295d4b5e03a3ed..deb9636b0ecf8f47e832a0b07e9e049ba19bdf16 100644
--- a/drivers/net/wireguard/device.c
+++ b/drivers/net/wireguard/device.c
@@ -210,7 +210,7 @@ static netdev_tx_t wg_xmit(struct sk_buff *skb, struct net_device *dev)
 	 */
 	while (skb_queue_len(&peer->staged_packet_queue) > MAX_STAGED_PACKETS) {
 		dev_kfree_skb(__skb_dequeue(&peer->staged_packet_queue));
-		++dev->stats.tx_dropped;
+		DEV_STATS_INC(dev, tx_dropped);
 	}
 	skb_queue_splice_tail(&packets, &peer->staged_packet_queue);
 	spin_unlock_bh(&peer->staged_packet_queue.lock);
@@ -228,7 +228,7 @@ static netdev_tx_t wg_xmit(struct sk_buff *skb, struct net_device *dev)
 	else if (skb->protocol == htons(ETH_P_IPV6))
 		icmpv6_ndo_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0);
 err:
-	++dev->stats.tx_errors;
+	DEV_STATS_INC(dev, tx_errors);
 	kfree_skb(skb);
 	return ret;
 }
-- 
2.43.0.rc0.421.g78406f8d94-goog