[moderation] [kernel?] KCSAN: data-race in copy_process / free_pid (11)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 54f71b0369c9 Merge tag 'rtc-6.10' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1190e60c980000
kernel config: https://syzkaller.appspot.com/x/.config?x=8d6784dd3500cda5
dashboard link: https://syzkaller.appspot.com/bug?extid=8fffe7b993f7d5d86fb3
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9746f6de3659/disk-54f71b03.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/923c9a224f99/vmlinux-54f71b03.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0d0d8e0df73c/bzImage-54f71b03.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8fffe7...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in copy_process / free_pid

read-write to 0xffffffff8605c4f8 of 4 bytes by task 6117 on cpu 1:
free_pid+0x80/0x170 kernel/pid.c:143
copy_process+0x19d0/0x1f90 kernel/fork.c:2637
kernel_clone+0x16a/0x570 kernel/fork.c:2797
__do_sys_clone3 kernel/fork.c:3098 [inline]
__se_sys_clone3+0x1b5/0x1f0 kernel/fork.c:3082
__x64_sys_clone3+0x31/0x40 kernel/fork.c:3082
x64_sys_call+0x28df/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:436
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 0xffffffff8605c4f8 of 4 bytes by task 32659 on cpu 0:
copy_process+0x15e3/0x1f90 kernel/fork.c:2543
kernel_clone+0x16a/0x570 kernel/fork.c:2797
user_mode_thread+0x7d/0xb0 kernel/fork.c:2875
call_usermodehelper_exec_work+0x41/0x150 kernel/umh.c:172
process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312
worker_thread+0x526/0x730 kernel/workqueue.c:3393
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

value changed: 0x800002a0 -> 0x8000029f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 32659 Comm: kworker/u8:10 Tainted: G W 6.9.0-syzkaller-12333-g54f71b0369c9 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Workqueue: events_unbound call_usermodehelper_exec_work
==================================================================


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