netdev - Re: [PATCH v2 net] wireguard: use DEV_STATS

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Date: Sat, 18 Nov 2023 14:58:03 +0800
From: Hangbin Liu <liuhangbin@...il.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: "David S . Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, eric.dumazet@...il.com,
	syzbot <syzkaller@...glegroups.com>,
	"Jason A . Donenfeld" <Jason@...c4.com>
Subject: Re: [PATCH v2 net] wireguard: use DEV_STATS_INC()

On Fri, Nov 17, 2023 at 02:17:33PM +0000, Eric Dumazet wrote:
> 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
> ...
> 
> v2: also change wg_packet_consume_data_done() (Hangbin Liu)
>     and wg_packet_purge_staged_packets()
> 
> 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>
> Cc: Hangbin Liu <liuhangbin@...il.com>
> ---

I respect Jason's comments.

Reviewed-by: Hangbin Liu <liuhangbin@...il.com>