[moderation] [kernel?] KCSAN: data-race in dequeue_signal / ptrace_check_attach (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 994d5c58e50e Merge tag 'hardening-v6.7-rc4' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1076ecbae80000
kernel config: https://syzkaller.appspot.com/x/.config?x=efc18f367a3f97fa
dashboard link: https://syzkaller.appspot.com/bug?extid=a9d474677b2657f19b49
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/77b2fa385c10/disk-994d5c58.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a10e02299372/vmlinux-994d5c58.xz
kernel image: https://storage.googleapis.com/syzbot-assets/73ebc6f961cc/bzImage-994d5c58.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a9d474...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in dequeue_signal / ptrace_check_attach

read-write to 0xffff8881230d8508 of 8 bytes by task 8600 on cpu 0:
dequeue_signal+0x3d3/0x420 kernel/signal.c:694
get_signal+0x36c/0x10a0 kernel/signal.c:2784
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:309
exit_to_user_mode_loop+0x6f/0xe0 kernel/entry/common.c:168
exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:296
do_syscall_64+0x50/0x110 arch/x86/entry/common.c:88
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881230d8508 of 8 bytes by task 8589 on cpu 1:
ptrace_freeze_traced kernel/ptrace.c:200 [inline]
ptrace_check_attach+0x7e/0x280 kernel/ptrace.c:267
__do_sys_ptrace kernel/ptrace.c:1300 [inline]
__se_sys_ptrace+0xd4/0x2a0 kernel/ptrace.c:1278
__x64_sys_ptrace+0x55/0x60 kernel/ptrace.c:1278
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000000000 -> 0x0000000008010000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8589 Comm: syz-executor.0 Not tainted 6.7.0-rc3-syzkaller-00134-g994d5c58e50e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================


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