KCSAN: data-race in ptrace_check_attach / zap_other_threads (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4ef8451b Merge tag 'perf-tools-for-v5.10-2020-11-03' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=105590dc500000
kernel config: https://syzkaller.appspot.com/x/.config?x=76dfc991796328d4
dashboard link: https://syzkaller.appspot.com/bug?extid=977ff1103c717b107726
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [ax...@kernel.dk chri...@brauner.io ebie...@xmission.com linux-...@vger.kernel.org liuzhi...@huawei.com ol...@redhat.com]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+977ff1...@syzkaller.appspotmail.com

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

read-write to 0xffff888134b5c4a8 of 8 bytes by task 14110 on cpu 1:
task_clear_jobctl_pending kernel/signal.c:344 [inline]
zap_other_threads+0x90/0x1d0 kernel/signal.c:1356
do_group_exit+0x140/0x170 kernel/exit.c:898
__do_sys_exit_group+0xb/0x10 kernel/exit.c:914
__se_sys_exit_group+0x5/0x10 kernel/exit.c:912
__x64_sys_exit_group+0x16/0x20 kernel/exit.c:912
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888134b5c4a8 of 8 bytes by task 14119 on cpu 0:
ptrace_freeze_traced kernel/ptrace.c:178 [inline]
ptrace_check_attach+0xdc/0x230 kernel/ptrace.c:247
__do_sys_ptrace kernel/ptrace.c:1272 [inline]
__se_sys_ptrace+0xdb/0x2e0 kernel/ptrace.c:1242
__x64_sys_ptrace+0x51/0x60 kernel/ptrace.c:1242
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14119 Comm: syz-executor.4 Not tainted 5.10.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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