KCSAN: data-race in do_notify_parent_cldstop / do_signal

KCSAN: data-race in do_notify_parent_cldstop / do_signal_stop (2)
Status: auto-closed as invalid on 2021/01/06 00:58
Reported-by: syzbot+fd6f1c0cf367341fd282@syzkaller.appspotmail.com
First crash: 336d, last: 330d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in do_notify_parent_cldstop / do_signal_stop (3)				3	259d	286d	0/22	auto-closed as invalid on 2021/03/17 11:58
upstream	KCSAN: data-race in do_notify_parent_cldstop / do_signal_stop				3	376d	388d	0/22	auto-closed as invalid on 2020/11/20 09:44

Sample crash report:

==================================================================
BUG: KCSAN: data-race in do_notify_parent_cldstop / do_signal_stop

write to 0xffff888100fae4e0 of 4 bytes by task 12822 on cpu 0:
 do_signal_stop+0x100/0x6b0 kernel/signal.c:2340
 get_signal+0xa83/0x1510 kernel/signal.c:2718
 arch_do_signal+0x25/0x260 arch/x86/kernel/signal.c:811
 exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
 exit_to_user_mode_prepare+0xde/0x170 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888100fae4e0 of 4 bytes by task 12798 on cpu 1:
 do_notify_parent_cldstop+0x1a1/0x290 kernel/signal.c:2055
 get_signal+0x44c/0x1510 kernel/signal.c:2592
 arch_do_signal+0x25/0x260 arch/x86/kernel/signal.c:811
 exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
 exit_to_user_mode_prepare+0xde/0x170 kernel/entry/common.c:191
 irqentry_exit_to_user_mode+0x5/0x20 kernel/entry/common.c:279
 irqentry_exit+0xe/0x40 kernel/entry/common.c:367
 asm_sysvec_reschedule_ipi+0x12/0x20 arch/x86/include/asm/idtentry.h:636

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12798 Comm: syz-executor.2 Not tainted 5.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (3):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info
ci2-upstream-kcsan-gce	2020/12/02 00:57	upstream	509a15421674	c42a35e9	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/29 13:41	upstream	aae5ab854e38	a0092f9d	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/25 05:34	upstream	127c501a03d5	1a1f4bd8	.config	log	report	info