KCSAN: data-race in do_signal_stop / futex_wait_queue

KCSAN: data-race in do_signal_stop / futex_wait_queue_me
Status: auto-closed as invalid on 2020/04/01 20:30
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 499d, last: 456d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in do_signal_stop / futex_wait_queue_me (2)				98	10h45m	190d	0/22	moderation: reported on 2020/10/15 10:01

Sample crash report:

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

read to 0xffff8881210c5090 of 8 bytes by task 14290 on cpu 0:
 do_signal_stop+0x3e3/0x500 kernel/signal.c:2348
 get_signal+0x61b/0x1320 kernel/signal.c:2694
 do_signal+0x2f/0x6c0 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x384/0x3a0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8881210c5090 of 8 bytes by task 14291 on cpu 1:
 futex_wait_queue_me+0x1f8/0x290 kernel/futex.c:2706
 futex_wait+0x19b/0x3f0 kernel/futex.c:2810
 do_futex+0xe9/0x18d0 kernel/futex.c:3881
 __do_sys_futex kernel/futex.c:3942 [inline]
 __se_sys_futex kernel/futex.c:3910 [inline]
 __x64_sys_futex+0x2cd/0x3f0 kernel/futex.c:3910
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14291 Comm: syz-executor.1 Not tainted 5.5.0-rc1-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
ci2-upstream-kcsan-gce	2020/01/22 20:26	https://github.com/google/ktsan.git kcsan	245a4300	3334d684	.config	log	report
ci2-upstream-kcsan-gce	2020/01/14 20:30	https://github.com/google/ktsan.git kcsan	245a4300	fa12bd3c	.config	log	report
ci2-upstream-kcsan-gce	2019/12/10 21:38	https://github.com/google/ktsan.git kcsan	ef798c30	101194eb	.config	log	report