[moderation] [kernel?] KCSAN: data-race in get_signal / ptrace_attach (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ab75170520d4 Merge tag 'linux-watchdog-6.13-rc6' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11a05418580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5e179f449c1ff36
dashboard link: https://syzkaller.appspot.com/bug?extid=e0175d320ca12ab5f0f3
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/1d0c9a686370/disk-ab751705.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a8479f48f80e/vmlinux-ab751705.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ad4632ba71cd/bzImage-ab751705.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e0175d...@syzkaller.appspotmail.com

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

write to 0xffff88815d1fa130 of 4 bytes by task 19659 on cpu 0:
ptrace_attach+0x258/0x520 kernel/ptrace.c:462
__do_sys_ptrace kernel/ptrace.c:1276 [inline]
__se_sys_ptrace+0x149/0x2b0 kernel/ptrace.c:1258
__x64_sys_ptrace+0x55/0x70 kernel/ptrace.c:1258
x64_sys_call+0x2225/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:102
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 0xffff88815d1fa130 of 4 bytes by task 19661 on cpu 1:
get_signal+0x3a0/0x1000 kernel/signal.c:2902
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
irqentry_exit_to_user_mode+0xa7/0x120 kernel/entry/common.c:231
irqentry_exit+0x12/0x50 kernel/entry/common.c:334
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 19661 Comm: syz.1.5127 Not tainted 6.13.0-rc5-syzkaller-00163-gab75170520d4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

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