[moderation] [kernel?] KCSAN: data-race in do_notify_parent_cldstop / wait_consider_task (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 36c254515dc6 Merge tag 'powerpc-6.12-4' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10ef885f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=a2f7ae2f221e9eae
dashboard link: https://syzkaller.appspot.com/bug?extid=fde24c31058861fe27ff
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-...@vger.kernel.org lu...@kernel.org pet...@infradead.org tg...@linutronix.de]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6637126dc14c/disk-36c25451.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7ed8be8b7151/vmlinux-36c25451.xz
kernel image: https://storage.googleapis.com/syzbot-assets/889c1c324bbe/bzImage-36c25451.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fde24c...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in do_notify_parent_cldstop / wait_consider_task

write to 0xffff888121e7851c of 4 bytes by task 24188 on cpu 0:
wait_task_stopped kernel/exit.c:1328 [inline]
wait_consider_task+0xaa8/0x1680 kernel/exit.c:1514
ptrace_do_wait kernel/exit.c:1554 [inline]
__do_wait+0x13e/0x500 kernel/exit.c:1662
do_wait+0xaf/0x270 kernel/exit.c:1692
kernel_wait4+0x164/0x1d0 kernel/exit.c:1851
__do_sys_wait4 kernel/exit.c:1879 [inline]
__se_sys_wait4 kernel/exit.c:1875 [inline]
__x64_sys_wait4+0x94/0x120 kernel/exit.c:1875
x64_sys_call+0x2529/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:62
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

read to 0xffff888121e7851c of 4 bytes by task 24190 on cpu 1:
do_notify_parent_cldstop+0x1a8/0x2a0 kernel/signal.c:2202
ptrace_stop+0x327/0x5a0 kernel/signal.c:2320
ptrace_signal+0x52/0x240 kernel/signal.c:2626
get_signal+0x820/0x1070 kernel/signal.c:2804
arch_do_signal_or_restart+0x95/0x4b0 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:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00000013 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 24190 Comm: syz.0.17335 Tainted: G W 6.12.0-rc2-syzkaller-00307-g36c254515dc6 #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

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