KCSAN: data-race in __ptrace_unlink / do

KCSAN: data-race in __ptrace_unlink / do_exit (5)
Status: auto-closed as invalid on 2021/06/15 19:49
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 218d, last: 208d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __ptrace_unlink / do_exit (3)	1	347d	347d	0/22	auto-closed as invalid on 2021/01/27 14:46
upstream	KCSAN: data-race in __ptrace_unlink / do_exit	4	468d	521d	0/22	auto-closed as invalid on 2020/09/28 07:37
upstream	KCSAN: data-race in __ptrace_unlink / do_exit (2)	4	394d	363d	0/22	auto-closed as invalid on 2020/12/21 11:46
upstream	KCSAN: data-race in __ptrace_unlink / do_exit (4)	1	287d	287d	0/22	auto-closed as invalid on 2021/03/28 11:03

Sample crash report:

==================================================================
BUG: KCSAN: data-race in __ptrace_unlink / do_exit

write to 0xffff888100930030 of 4 bytes by task 27395 on cpu 1:
 __ptrace_unlink+0x162/0x320 kernel/ptrace.c:133
 __ptrace_detach+0x1b/0x1d0 kernel/ptrace.c:523
 exit_ptrace+0x93/0x160 kernel/ptrace.c:583
 forget_original_parent kernel/exit.c:629 [inline]
 exit_notify kernel/exit.c:669 [inline]
 do_exit+0x126d/0x1560 kernel/exit.c:846
 do_group_exit+0xce/0x1a0 kernel/exit.c:923
 get_signal+0xfc3/0x1610 kernel/signal.c:2818
 arch_do_signal_or_restart+0x2a/0x220 arch/x86/kernel/signal.c:789
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x109/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888100930030 of 4 bytes by task 27390 on cpu 0:
 ptrace_event_enabled include/linux/ptrace.h:142 [inline]
 ptrace_event include/linux/ptrace.h:157 [inline]
 do_exit+0x101/0x1560 kernel/exit.c:766
 do_group_exit+0xce/0x1a0 kernel/exit.c:923
 get_signal+0xfc3/0x1610 kernel/signal.c:2818
 arch_do_signal_or_restart+0x2a/0x220 arch/x86/kernel/signal.c:789
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x109/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 27390 Comm: syz-executor.4 Not tainted 5.13.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2021/05/11 19:44	upstream	88b06399c9c7	b3c3bb8e	.config	log	report			info	KCSAN: data-race in __ptrace_unlink / do_exit
ci2-upstream-kcsan-gce	2021/05/01 02:03	upstream	65c61de9d090	77e2b668	.config	log	report			info	KCSAN: data-race in __ptrace_unlink / do_exit