Re: [PATCH net] packet: annotate data-races around ignore_outgoing

From: Jason Xing <kerneljasonxing@gmail.com>
To: Eric Dumazet <edumazet@google.com>
Cc: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	 Paolo Abeni <pabeni@redhat.com>,
	netdev@vger.kernel.org, eric.dumazet@gmail.com,
	 syzbot+c669c1136495a2e7c31f@syzkaller.appspotmail.com,
	 Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Subject: Re: [PATCH net] packet: annotate data-races around ignore_outgoing
Date: Fri, 15 Mar 2024 10:22:51 +0800	[thread overview]
Message-ID: <CAL+tcoCzSc2YONPuwgC7f9ogKVndHzUcX9PMizgHHQ=1wqChKw@mail.gmail.com> (raw)
In-Reply-To: <20240314141816.2640229-1-edumazet@google.com>

On Thu, Mar 14, 2024 at 10:18 PM Eric Dumazet <edumazet@google.com> wrote:
>
> ignore_outgoing is read locklessly from dev_queue_xmit_nit()
> and packet_getsockopt()
>
> Add appropriate READ_ONCE()/WRITE_ONCE() annotations.
>
> syzbot reported:
>
> BUG: KCSAN: data-race in dev_queue_xmit_nit / packet_setsockopt
>
> write to 0xffff888107804542 of 1 bytes by task 22618 on cpu 0:
>  packet_setsockopt+0xd83/0xfd0 net/packet/af_packet.c:4003
>  do_sock_setsockopt net/socket.c:2311 [inline]
>  __sys_setsockopt+0x1d8/0x250 net/socket.c:2334
>  __do_sys_setsockopt net/socket.c:2343 [inline]
>  __se_sys_setsockopt net/socket.c:2340 [inline]
>  __x64_sys_setsockopt+0x66/0x80 net/socket.c:2340
>  do_syscall_64+0xd3/0x1d0
>  entry_SYSCALL_64_after_hwframe+0x6d/0x75
>
> read to 0xffff888107804542 of 1 bytes by task 27 on cpu 1:
>  dev_queue_xmit_nit+0x82/0x620 net/core/dev.c:2248
>  xmit_one net/core/dev.c:3527 [inline]
>  dev_hard_start_xmit+0xcc/0x3f0 net/core/dev.c:3547
>  __dev_queue_xmit+0xf24/0x1dd0 net/core/dev.c:4335
>  dev_queue_xmit include/linux/netdevice.h:3091 [inline]
>  batadv_send_skb_packet+0x264/0x300 net/batman-adv/send.c:108
>  batadv_send_broadcast_skb+0x24/0x30 net/batman-adv/send.c:127
>  batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:392 [inline]
>  batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:420 [inline]
>  batadv_iv_send_outstanding_bat_ogm_packet+0x3f0/0x4b0 net/batman-adv/bat_iv_ogm.c:1700
>  process_one_work kernel/workqueue.c:3254 [inline]
>  process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335
>  worker_thread+0x526/0x730 kernel/workqueue.c:3416
>  kthread+0x1d1/0x210 kernel/kthread.c:388
>  ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
>
> value changed: 0x00 -> 0x01
>
> Reported by Kernel Concurrency Sanitizer on:
> CPU: 1 PID: 27 Comm: kworker/u8:1 Tainted: G        W          6.8.0-syzkaller-08073-g480e035fc4c7 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
> Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
>
> Fixes: fa788d986a3a ("packet: add sockopt to ignore outgoing packets")
> Reported-by: syzbot+c669c1136495a2e7c31f@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/netdev/CANn89i+Z7MfbkBLOv=p7KZ7=K1rKHO4P1OL5LYDCtBiyqsa9oQ@mail.gmail.com/T/#t
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>

Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>

Thanks!