[moderation] [kernel?] KCSAN: data-race in copy_process / free_pid (14)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 63676eefb7a0 Merge tag 'sched_ext-for-6.13-rc5-fixes' of g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11e238b0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5e179f449c1ff36
dashboard link: https://syzkaller.appspot.com/bug?extid=fab52e3459fa2f95df57
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/867eb8fde4e1/disk-63676eef.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a4c43dfe0999/vmlinux-63676eef.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9b651cd4799d/bzImage-63676eef.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fab52e...@syzkaller.appspotmail.com

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

read-write to 0xffffffff8665d9f8 of 4 bytes by task 11702 on cpu 1:
free_pid+0x80/0x170 kernel/pid.c:143
copy_process+0x1213/0x1f90 kernel/fork.c:2644
kernel_clone+0x167/0x5e0 kernel/fork.c:2806
__do_sys_clone kernel/fork.c:2949 [inline]
__se_sys_clone kernel/fork.c:2933 [inline]
__x64_sys_clone+0xe8/0x120 kernel/fork.c:2933
x64_sys_call+0x2d7e/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:57
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 0xffffffff8665d9f8 of 4 bytes by task 7608 on cpu 0:
copy_process+0x1799/0x1f90 kernel/fork.c:2549
kernel_clone+0x167/0x5e0 kernel/fork.c:2806
user_mode_thread+0x7d/0xb0 kernel/fork.c:2884
call_usermodehelper_exec_sync kernel/umh.c:132 [inline]
call_usermodehelper_exec_work+0x7a/0x150 kernel/umh.c:163
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

value changed: 0x80000116 -> 0x80000115

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7608 Comm: kworker/u8:56 Not tainted 6.13.0-rc5-syzkaller-00161-g63676eefb7a0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: events_unbound call_usermodehelper_exec_work
==================================================================


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