[moderation] [net?] KCSAN: data-race in cleanup_net / synchronize_net (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 546b1c9e93c2 Merge tag 'bootconfig-v6.16' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15b6380c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=820f700375f19064
dashboard link: https://syzkaller.appspot.com/bug?extid=73335de84bbbc77a7cd1
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
CC: [da...@davemloft.net edum...@google.com ho...@kernel.org ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org pab...@redhat.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8466aeec3910/disk-546b1c9e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/92921e47937a/vmlinux-546b1c9e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/204e95f266ef/bzImage-546b1c9e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+73335d...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in cleanup_net / synchronize_net

write to 0xffffffff88fec498 of 8 bytes by task 3434 on cpu 0:
cleanup_net+0x50/0x4d0 net/core/net_namespace.c:657
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3321
worker_thread+0x582/0x770 kernel/workqueue.c:3402
kthread+0x486/0x510 kernel/kthread.c:464
ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff88fec498 of 8 bytes by task 9187 on cpu 1:
from_cleanup_net net/core/dev.c:10501 [inline]
synchronize_net+0x24/0x70 net/core/dev.c:11925
packet_release+0x5d2/0x810 net/packet/af_packet.c:3217
__sock_release net/socket.c:647 [inline]
sock_close+0x68/0x150 net/socket.c:1391
__fput+0x298/0x650 fs/file_table.c:465
____fput+0x1c/0x30 fs/file_table.c:493
task_work_run+0x12e/0x1a0 kernel/task_work.c:227
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x47f/0x1590 kernel/exit.c:955
do_group_exit+0xff/0x140 kernel/exit.c:1104
get_signal+0xe59/0xf70 kernel/signal.c:3034
arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
irqentry_exit_to_user_mode+0x5e/0xa0 kernel/entry/common.c:184
irqentry_exit+0x12/0x50 kernel/entry/common.c:287
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

value changed: 0x0000000000000000 -> 0xffff888104278000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 9187 Comm: syz.6.10189 Not tainted 6.15.0-syzkaller-11173-g546b1c9e93c2 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.