KCSAN: data-race in acct_collect / do_exit (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 407ab579 Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14beb142500000
kernel config: https://syzkaller.appspot.com/x/.config?x=671e27f23e60a67b
dashboard link: https://syzkaller.appspot.com/bug?extid=831bcf3a0460901c5be6
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [ak...@linux-foundation.org chri...@brauner.io ebie...@xmission.com linux-...@vger.kernel.org min...@kernel.org mi...@kernel.org pet...@infradead.org tg...@linutronix.de]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+831bcf...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in acct_collect / do_exit

write to 0xffff88807ee9f49c of 4 bytes by task 31657 on cpu 0:
reparent_leader kernel/exit.c:582 [inline]
forget_original_parent kernel/exit.c:634 [inline]
exit_notify kernel/exit.c:650 [inline]
do_exit+0x8de/0x15a0 kernel/exit.c:826
do_group_exit+0xc8/0x170 kernel/exit.c:903
get_signal+0xf9b/0x1510 kernel/signal.c:2758
arch_do_signal+0x25/0x260 arch/x86/kernel/signal.c:811
exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
exit_to_user_mode_prepare+0xde/0x170 kernel/entry/common.c:191
syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88807ee9f49c of 4 bytes by task 31658 on cpu 1:
thread_group_leader include/linux/sched/signal.h:654 [inline]
acct_collect+0x14c/0x360 kernel/acct.c:556
do_exit+0x373/0x15a0 kernel/exit.c:785
__seccomp_filter+0xe40/0xe60 kernel/seccomp.c:1038
__secure_computing+0x12e/0x1c0 kernel/seccomp.c:1074
syscall_trace_enter+0x106/0x290 kernel/entry/common.c:58
__syscall_enter_from_user_work kernel/entry/common.c:81 [inline]
syscall_enter_from_user_mode+0x1d/0x20 kernel/entry/common.c:99
do_syscall_64+0x11/0x80 arch/x86/entry/common.c:41
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 31658 Comm: syz-executor.1 Not tainted 5.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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