[moderation] [kernel?] KCSAN: data-race in memcpy_and_pad / zap_other_threads

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 07d9df80082b Merge tag 'perf-tools-fixes-for-v6.17-2025-08..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=124d2262580000
kernel config: https://syzkaller.appspot.com/x/.config?x=86a2212b48ce4ce2
dashboard link: https://syzkaller.appspot.com/bug?extid=09ff6ebfc22191ecf441
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
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/4d171f55c84c/disk-07d9df80.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a98c7e116e81/vmlinux-07d9df80.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7681910e0d3d/bzImage-07d9df80.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+09ff6e...@syzkaller.appspotmail.com

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

read-write to 0xffff888104b40538 of 8 bytes by task 26415 on cpu 1:
task_clear_jobctl_pending kernel/signal.c:339 [inline]
zap_other_threads+0x114/0x290 kernel/signal.c:1345
do_group_exit+0xe4/0x140 kernel/exit.c:1097
__do_sys_exit_group kernel/exit.c:1113 [inline]
__se_sys_exit_group kernel/exit.c:1111 [inline]
__x64_sys_exit_group+0x1f/0x20 kernel/exit.c:1111
x64_sys_call+0x2fe2/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888104b40000 of 3264 bytes by task 26416 on cpu 0:
memcpy_and_pad+0x48/0x80 lib/string_helpers.c:1007
arch_dup_task_struct+0x2c/0x40 arch/x86/kernel/process.c:98
dup_task_struct+0x83/0x6a0 kernel/fork.c:878
copy_process+0x399/0x2000 kernel/fork.c:2004
create_io_thread+0x93/0xc0 kernel/fork.c:2553
io_sq_offload_create+0x652/0x850 io_uring/sqpoll.c:491
io_uring_create+0x42e/0x610 io_uring/io_uring.c:3808
io_uring_setup io_uring/io_uring.c:3891 [inline]
__do_sys_io_uring_setup io_uring/io_uring.c:3925 [inline]
__se_sys_io_uring_setup+0x1f7/0x210 io_uring/io_uring.c:3916
__x64_sys_io_uring_setup+0x31/0x40 io_uring/io_uring.c:3916
x64_sys_call+0x2b21/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:426
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 26416 Comm: syz.0.7528 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================


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[syzbot]

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