KCSAN: data-race in do_exit / exit

KCSAN: data-race in do_exit / exit_signals (3)
Status: auto-closed as invalid on 2021/03/13 07:46
Reported-by: syzbot+74d5dfab4b8a37e04f6b@syzkaller.appspotmail.com
First crash: 292d, last: 223d

similar bugs (3):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in do_exit / exit_signals	1	437d	437d	0/22	auto-closed as invalid on 2020/08/11 13:36
upstream	KCSAN: data-race in do_exit / exit_signals (4)	4	124d	161d	0/22	auto-closed as invalid on 2021/06/20 08:01
upstream	KCSAN: data-race in do_exit / exit_signals (2)	3	364d	382d	0/22	auto-closed as invalid on 2020/10/22 22:12

Sample crash report:

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

write to 0xffff8880227e102c of 4 bytes by task 15703 on cpu 0:
 exit_signals+0x10d/0x540 kernel/signal.c:2865
 do_exit+0x1b4/0x1690 kernel/exit.c:781
 do_group_exit+0xce/0x180 kernel/exit.c:922
 get_signal+0xdce/0x14e0 kernel/signal.c:2773
 arch_do_signal_or_restart+0x2a/0x270 arch/x86/kernel/signal.c:811
 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+0x11a/0x1b0 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880227e102c of 4 bytes by task 15673 on cpu 1:
 find_alive_thread kernel/exit.c:511 [inline]
 find_new_reaper kernel/exit.c:560 [inline]
 forget_original_parent kernel/exit.c:635 [inline]
 exit_notify kernel/exit.c:668 [inline]
 do_exit+0x59c/0x1690 kernel/exit.c:845
 do_group_exit+0xce/0x180 kernel/exit.c:922
 get_signal+0xdce/0x14e0 kernel/signal.c:2773
 arch_do_signal_or_restart+0x2a/0x270 arch/x86/kernel/signal.c:811
 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+0x11a/0x1b0 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15673 Comm: syz-executor.3 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (7):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/02/06 07:45	upstream	1e0d27fce010	23a562df	.config	log	report	info	KCSAN: data-race in do_exit / exit_signals
ci2-upstream-kcsan-gce	2021/01/28 21:50	upstream	e5ff2cb9cf67	7df34f59	.config	log	report	info	KCSAN: data-race in do_exit / exit_signals
ci2-upstream-kcsan-gce	2021/01/23 10:51	upstream	fe75a21824e7	52e37319	.config	log	report	info	KCSAN: data-race in do_exit / exit_signals
ci2-upstream-kcsan-gce	2021/01/08 21:10	upstream	6279d812eab6	c104d4a3	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/03 18:22	upstream	3516bd729358	79264ae3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/24 05:21	upstream	58cf05f597b0	c2c1d1dd	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/29 05:01	upstream	67f34fa8893e	a0092f9d	.config	log	report	info