syzbot

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BUG: KCSAN: data-race in dequeue_signal / ptrace_check_attach

read-write to 0xffff888109f20538 of 8 bytes by task 5737 on cpu 1:
 dequeue_signal+0x309/0x3b0 kernel/signal.c:656
 get_signal+0x377/0xf70 kernel/signal.c:2914
 arch_do_signal_or_restart+0x97/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x68/0xb0 kernel/entry/common.c:218
 do_syscall_64+0xdd/0x1a0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888109f20538 of 8 bytes by task 5736 on cpu 0:
 ptrace_freeze_traced kernel/ptrace.c:189 [inline]
 ptrace_check_attach+0xaa/0x290 kernel/ptrace.c:256
 __do_sys_ptrace kernel/ptrace.c:1280 [inline]
 __se_sys_ptrace+0xd3/0x2b0 kernel/ptrace.c:1258
 __x64_sys_ptrace+0x55/0x70 kernel/ptrace.c:1258
 x64_sys_call+0x1d6a/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:102
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0x0000000008010000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 5736 Comm: syz.4.13755 Not tainted 6.15.0-rc5-syzkaller-00136-g9c69f8884904 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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