[moderation] [perf?] KCSAN: data-race in memcpy_and_pad / perf_remove_from_owner

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 42bddab0563f Merge tag 'execve-v7.0-rc5' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16adbada580000
kernel config: https://syzkaller.appspot.com/x/.config?x=3a78dd265deac3a9
dashboard link: https://syzkaller.appspot.com/bug?extid=eacca7447d304884ae62
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [ac...@kernel.org adrian...@intel.com alexander...@linux.intel.com iro...@google.com james...@linaro.org jo...@kernel.org linux-...@vger.kernel.org linux-pe...@vger.kernel.org mark.r...@arm.com mi...@redhat.com namh...@kernel.org pet...@infradead.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8a4ebc6526e5/disk-42bddab0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/45b3f7857fa4/vmlinux-42bddab0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/07bea84415ae/bzImage-42bddab0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+eacca7...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in memcpy_and_pad / perf_remove_from_owner

write to 0xffff888104c28a10 of 8 bytes by task 17291 on cpu 0:
__list_del include/linux/list.h:203 [inline]
__list_del_entry include/linux/list.h:226 [inline]
list_del_init include/linux/list.h:295 [inline]
perf_remove_from_owner+0xe6/0x1f0 kernel/events/core.c:5897
perf_event_release_kernel+0x6a/0x510 kernel/events/core.c:5941
perf_release+0x1f/0x30 kernel/events/core.c:6033
__fput+0x29b/0x650 fs/file_table.c:469
____fput+0x1c/0x30 fs/file_table.c:497
task_work_run+0x130/0x1a0 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
exit_to_user_mode_loop+0x1f4/0x6f0 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888104c28000 of 3328 bytes by task 17292 on cpu 1:
memcpy_and_pad+0x48/0x80 lib/string_helpers.c:1008
arch_dup_task_struct+0x2c/0x40 arch/x86/kernel/process.c:108
dup_task_struct+0x6e/0x950 kernel/fork.c:920
copy_process+0x37e/0x20b0 kernel/fork.c:2050
create_io_thread+0x8f/0xc0 kernel/fork.c:2601
create_worker_cont+0x5f/0x380 io_uring/io-wq.c:852
task_work_run+0x130/0x1a0 kernel/task_work.c:233
get_signal+0xe0e/0xf60 kernel/signal.c:2807
arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
exit_to_user_mode_loop+0x6a/0x6f0 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 17292 Comm: syz.3.2996 Tainted: G W syzkaller #0 PREEMPT(full)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup