syzbot

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BUG: KCSAN: data-race in prepare_signal / ptrace_attach

write to 0xffff8881014a52b0 of 4 bytes by task 14654 on cpu 1:
 ptrace_attach+0x230/0x4f0 kernel/ptrace.c:462
 __do_sys_ptrace kernel/ptrace.c:1276 [inline]
 __se_sys_ptrace+0x146/0x2b0 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

read to 0xffff8881014a52b0 of 4 bytes by task 14655 on cpu 0:
 sig_ignored kernel/signal.c:121 [inline]
 prepare_signal+0x450/0x670 kernel/signal.c:935
 __send_signal_locked+0x30/0x760 kernel/signal.c:1053
 send_signal_locked+0x34e/0x3c0 kernel/signal.c:1216
 force_sig_info_to_task+0x1fb/0x290 kernel/signal.c:1320
 force_sig_fault_to_task kernel/signal.c:1699 [inline]
 force_sig_fault+0x71/0xa0 kernel/signal.c:1704
 __bad_area_nosemaphore+0x25d/0x330 arch/x86/mm/fault.c:824
 handle_page_fault arch/x86/mm/fault.c:1478 [inline]
 exc_page_fault+0x6d/0xc0 arch/x86/mm/fault.c:1538
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 14655 Comm: syz.6.3454 Not tainted 6.15.0-rc5-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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