syzbot

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BUG: KCSAN: data-race in prepare_signal / ptrace_attach

write to 0xffff88811776e330 of 4 bytes by task 10179 on cpu 0:
 ptrace_attach+0x258/0x520 kernel/ptrace.c:462
 __do_sys_ptrace kernel/ptrace.c:1276 [inline]
 __se_sys_ptrace+0x149/0x2b0 kernel/ptrace.c:1258
 __x64_sys_ptrace+0x55/0x70 kernel/ptrace.c:1258
 x64_sys_call+0x2225/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:102
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811776e330 of 4 bytes by task 10180 on cpu 1:
 prepare_signal+0x263/0x670 kernel/signal.c:901
 __send_signal_locked+0x2f/0x780 kernel/signal.c:1052
 send_signal_locked+0x28f/0x3a0 kernel/signal.c:1215
 do_send_sig_info+0x9f/0xf0 kernel/signal.c:1268
 do_send_specific kernel/signal.c:4091 [inline]
 do_tkill kernel/signal.c:4112 [inline]
 __do_sys_tkill kernel/signal.c:4147 [inline]
 __se_sys_tkill+0x135/0x190 kernel/signal.c:4141
 __x64_sys_tkill+0x31/0x40 kernel/signal.c:4141
 x64_sys_call+0x281a/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:201
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000 -> 0x00010001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 10180 Comm: syz.1.2207 Not tainted 6.13.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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