syzbot

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BUG: KCSAN: data-race in get_signal / ptrace_attach

write to 0xffff8881535eb0f0 of 4 bytes by task 23583 on cpu 1:
 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+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881535eb0f0 of 4 bytes by task 23584 on cpu 0:
 get_signal+0x396/0x10a0 kernel/signal.c:2779
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:105 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:201 [inline]
 syscall_exit_to_user_mode+0x58/0x120 kernel/entry/common.c:212
 do_syscall_64+0xda/0x1d0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 23584 Comm: syz-executor.0 Not tainted 6.8.0-rc6-syzkaller-00037-g805d849d7c3c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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