[moderation] [fs?] KCSAN: data-race in drop_sysctl_table / proc_sys_revalidate

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bf9aa14fc523 Merge tag 'timers-core-2024-11-18' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13774ae8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a4239a0e02e161ec
dashboard link: https://syzkaller.appspot.com/bug?extid=0f36826deffa40789116
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [joel.g...@kernel.org ke...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org mcg...@kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5889d7019bad/disk-bf9aa14f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8d0c07d02151/vmlinux-bf9aa14f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bafa60632b80/bzImage-bf9aa14f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0f3682...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in drop_sysctl_table / proc_sys_revalidate

write to 0xffff88810aabe858 of 8 bytes by task 9 on cpu 0:
start_unregistering fs/proc/proc_sysctl.c:303 [inline]
drop_sysctl_table+0x97/0x260 fs/proc/proc_sysctl.c:1506
drop_sysctl_table+0x1cd/0x260 fs/proc/proc_sysctl.c:1513
unregister_sysctl_table+0x30/0x50 fs/proc/proc_sysctl.c:1531
unregister_net_sysctl_table+0x15/0x20 net/sysctl_net.c:177
__devinet_sysctl_unregister net/ipv4/devinet.c:2633 [inline]
devinet_sysctl_unregister net/ipv4/devinet.c:2661 [inline]
inetdev_destroy net/ipv4/devinet.c:345 [inline]
inetdev_event+0x614/0xad0 net/ipv4/devinet.c:1643
notifier_call_chain kernel/notifier.c:93 [inline]
raw_notifier_call_chain+0x6f/0x1d0 kernel/notifier.c:461
call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:1996
call_netdevice_notifiers_extack net/core/dev.c:2034 [inline]
call_netdevice_notifiers net/core/dev.c:2048 [inline]
unregister_netdevice_many_notify+0x8b7/0x11b0 net/core/dev.c:11407
unregister_netdevice_many net/core/dev.c:11469 [inline]
unregister_netdevice_queue+0x1f4/0x220 net/core/dev.c:11343
unregister_netdevice include/linux/netdevice.h:3118 [inline]
ser_release+0x118/0x180 drivers/net/caif/caif_serial.c:310
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
kthread+0x1d1/0x210 kernel/kthread.c:389
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff88810aabe858 of 8 bytes by task 3054 on cpu 1:
proc_sys_revalidate+0x49/0x70 fs/proc/proc_sysctl.c:885
lookup_fast+0x177/0x2a0
walk_component fs/namei.c:2108 [inline]
link_path_walk+0x464/0x820 fs/namei.c:2477
path_openat+0x1af/0x1fa0 fs/namei.c:3983
do_filp_open+0x107/0x230 fs/namei.c:4014
do_sys_openat2+0xab/0x120 fs/open.c:1398
do_sys_open fs/open.c:1413 [inline]
__do_sys_openat fs/open.c:1429 [inline]
__se_sys_openat fs/open.c:1424 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1424
x64_sys_call+0x2b30/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffffffffffffffea

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3054 Comm: dhcpcd Not tainted 6.12.0-syzkaller-01782-gbf9aa14fc523 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
==================================================================


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[syzbot]

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