[moderation] [kernel?] KCSAN: data-race in get_signal / ptrace_attach (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 805d849d7c3c Merge tag 'acpi-6.8-rc7' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10f91c6a180000
kernel config: https://syzkaller.appspot.com/x/.config?x=53006d590acdf777
dashboard link: https://syzkaller.appspot.com/bug?extid=f4a233287323b2ec5e4c
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/c550e093323d/disk-805d849d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/42cd67389a8e/vmlinux-805d849d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/90500a18c974/bzImage-805d849d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f4a233...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in get_signal / ptrace_attach

write to 0xffff8881535eb0f0 of 4 bytes by task 23583 on cpu 1:
ptrace_attach+0x31c/0x590 kernel/ptrace.c:459
__do_sys_ptrace kernel/ptrace.c:1279 [inline]
__se_sys_ptrace+0x149/0x2a0 kernel/ptrace.c:1261
__x64_sys_ptrace+0x55/0x60 kernel/ptrace.c:1261
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881535eb0f0 of 4 bytes by task 23584 on cpu 0:
get_signal+0x396/0x10a0 kernel/signal.c:2779
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop kernel/entry/common.c:105 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:201 [inline]
syscall_exit_to_user_mode+0x58/0x120 kernel/entry/common.c:212
do_syscall_64+0xda/0x1d0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 23584 Comm: syz-executor.0 Not tainted 6.8.0-rc6-syzkaller-00037-g805d849d7c3c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================


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[syzbot]

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