syzbot

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BUG: KCSAN: data-race in ptrace_check_attach / ptrace_stop

read-write to 0xffff888101bf2dc0 of 8 bytes by task 3106 on cpu 0:
 ptrace_stop+0xcc/0x590 kernel/signal.c:2254
 do_jobctl_trap+0x198/0x1e0
 get_signal+0x975/0xff0 kernel/signal.c:2729
 arch_do_signal_or_restart+0x89/0x2a0 arch/x86/kernel/signal.c:306
 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:286 [inline]
 syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:297
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888101bf2dc0 of 8 bytes by task 9365 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:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000100000 -> 0x0000000008000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9365 Comm: syz-executor.4 Not tainted 6.4.0-rc6-syzkaller-00195-g40f71e7cd3c6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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