syzbot

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BUG: KCSAN: data-race in prepare_signal / ptrace_attach

write to 0xffff8881530b4e30 of 4 bytes by task 24545 on cpu 1:
 ptrace_attach+0x23d/0x3f0 kernel/ptrace.c:450
 __do_sys_ptrace kernel/ptrace.c:1312 [inline]
 __se_sys_ptrace+0xc1/0x2d0 kernel/ptrace.c:1292
 __x64_sys_ptrace+0x51/0x60 kernel/ptrace.c:1292
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881530b4e30 of 4 bytes by task 24546 on cpu 0:
 sig_ignored kernel/signal.c:116 [inline]
 prepare_signal+0xb78/0xda0 kernel/signal.c:965
 __send_signal+0x63/0x740 kernel/signal.c:1085
 send_signal+0x38f/0x3a0 kernel/signal.c:1248
 force_sig_info_to_task+0x2b4/0x360 kernel/signal.c:1350
 force_sig_fault_to_task kernel/signal.c:1721 [inline]
 force_sig_fault+0x61/0x90 kernel/signal.c:1727
 __bad_area_nosemaphore+0x267/0x300 arch/x86/mm/fault.c:846
 handle_page_fault arch/x86/mm/fault.c:1482 [inline]
 exc_page_fault+0x81/0x160 arch/x86/mm/fault.c:1540
 asm_exc_page_fault+0x1e/0x30

value changed: 0x00000000 -> 0x00010001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 24546 Comm: syz-executor.3 Not tainted 5.18.0-rc7-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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