[moderation] [kernel?] KCSAN: data-race in prepare_signal / ptrace_attach (10)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4854cf9c61d0 Merge tag 'mips-fixes_6.8_1' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=163939a7e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bd33f45956bbc2
dashboard link: https://syzkaller.appspot.com/bug?extid=08ca189817ae7e7c8a29
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-...@vger.kernel.org ol...@redhat.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e44f160651d1/disk-4854cf9c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f6a2062d07e6/vmlinux-4854cf9c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3d179908ef3c/bzImage-4854cf9c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+08ca18...@syzkaller.appspotmail.com

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

write to 0xffff888129e820b0 of 4 bytes by task 13931 on cpu 0:
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+0x59/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888129e820b0 of 4 bytes by task 13932 on cpu 1:
sig_ignored kernel/signal.c:118 [inline]
prepare_signal+0x45a/0x660 kernel/signal.c:966
__send_signal_locked+0x2f/0x700 kernel/signal.c:1084
send_signal_locked+0x28d/0x3a0 kernel/signal.c:1247
force_sig_info_to_task+0x1ec/0x280 kernel/signal.c:1351
force_sig_fault_to_task kernel/signal.c:1726 [inline]
force_sig_fault+0x73/0xa0 kernel/signal.c:1731
__bad_area_nosemaphore+0x263/0x320 arch/x86/mm/fault.c:857
handle_page_fault arch/x86/mm/fault.c:1505 [inline]
exc_page_fault+0x500/0x6d0 arch/x86/mm/fault.c:1563
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570

value changed: 0x00000000 -> 0x00010001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13932 Comm: syz-executor.2 Not tainted 6.8.0-rc1-syzkaller-00385-g4854cf9c61d0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
==================================================================


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[syzbot]

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