Subject: Re: [PATCH net] l2tp: avoid one data-race in l2tp_tunnel_del_work()

From: [email-masked]
Date: Mon, 19 Jan 2026 18:00:05 +0000

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <[email-masked]>:

On Thu, 15 Jan 2026 09:21:39 +0000 you wrote:
> We should read sk->sk_socket only when dealing with kernel sockets.
> 
> syzbot reported the following data-race:
> 
> BUG: KCSAN: data-race in l2tp_tunnel_del_work / sk_common_release
> 
> write to 0xffff88811c182b20 of 8 bytes by task 5365 on cpu 0:
>   sk_set_socket include/net/sock.h:2092 [inline]
>   sock_orphan include/net/sock.h:2118 [inline]
>   sk_common_release+0xae/0x230 net/core/sock.c:4003
>   udp_lib_close+0x15/0x20 include/net/udp.h:325
>   inet_release+0xce/0xf0 net/ipv4/af_inet.c:437
>   __sock_release net/socket.c:662 [inline]
>   sock_close+0x6b/0x150 net/socket.c:1455
>   __fput+0x29b/0x650 fs/file_table.c:468
>   ____fput+0x1c/0x30 fs/file_table.c:496
>   task_work_run+0x131/0x1a0 kernel/task_work.c:233
>   resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
>   __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
>   exit_to_user_mode_loop+0x1fe/0x740 kernel/entry/common.c:75
>   __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
>   syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
>   syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
>   syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
>   do_syscall_64+0x1e1/0x2b0 arch/x86/entry/syscall_64.c:100
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> [...]

Here is the summary with links:
  - [net] l2tp: avoid one data-race in l2tp_tunnel_del_work()
    https://git.kernel.org/netdev/net/c/7a29f6bf60f2

You are awesome, thank you!
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