KCSAN: data-race in exit_signals / kthread

KCSAN: data-race in exit_signals / kthread_unpark (3)
Status: moderation: reported on 2020/12/07 11:34
Reported-by: syzbot+3cf231e9e732c716afe4@syzkaller.appspotmail.com
First crash: 288d, last: 3h11m

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in exit_signals / kthread_unpark				3	533d	536d	0/22	closed as invalid on 2019/11/19 13:44
upstream	KCSAN: data-race in exit_signals / kthread_unpark (2)				19	317d	516d	0/22	closed as invalid on 2020/06/18 14:24

Sample crash report:

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

write to 0xffff88813b7e602c of 4 bytes by task 17424 on cpu 0:
 exit_signals+0xe1/0x4a0 kernel/signal.c:2873
 do_exit+0x194/0x1560 kernel/exit.c:781
 kthread+0x1d8/0x1f0 kernel/kthread.c:294
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88813b7e602c of 4 bytes by task 17401 on cpu 1:
 to_kthread kernel/kthread.c:83 [inline]
 kthread_unpark+0x1f/0x150 kernel/kthread.c:536
 kthread_stop+0xa6/0x250 kernel/kthread.c:619
 loop_unprepare_queue drivers/block/loop.c:926 [inline]
 __loop_clr_fd+0x4d1/0x650 drivers/block/loop.c:1257
 loop_clr_fd drivers/block/loop.c:1336 [inline]
 lo_ioctl+0x9eb/0x11f0 drivers/block/loop.c:1694
 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:583
 block_ioctl+0x6d/0x80 fs/block_dev.c:1671
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 17401 Comm: syz-executor.2 Not tainted 5.12.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (46):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/04/21 05:29	upstream	1fe5501b	c0ced557	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/04/16 20:36	upstream	2f7b98d1	7e2b734b	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/03/30 05:43	upstream	1e43c377	6a81331a	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/03/28 23:08	upstream	36a14638	a8529b82	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/03/27 08:12	upstream	0f4498ce	a8529b82	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/03/26 13:09	upstream	db24726b	a8529b82	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/03/22 03:52	upstream	5ee96fa9	bea32f74	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/03/17 06:09	upstream	1df27313	fdb2bb2c	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/03/16 07:12	upstream	1a4431a5	fdb2bb2c	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/03/16 01:49	upstream	1e28eed1	fdb2bb2c	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/03/14 16:27	upstream	88fe4924	4a003785	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/02/21 16:37	upstream	e767b353	3e5ed8b4	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/02/21 03:23	upstream	f40ddce8	3e5ed8b4	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/02/20 09:26	upstream	f40ddce8	f689d40a	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/02/11 19:21	upstream	291009f6	a5f86b15	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/02/11 10:39	upstream	291009f6	a52ee10a	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/01/27 02:44	upstream	13391c60	55a7d4df	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/01/24 10:43	upstream	e1ae4b0b	52e37319	.config	log	report	info	KCSAN: data-race in exit_signals / kthread_unpark
ci2-upstream-kcsan-gce	2021/01/05 11:55	upstream	36bbbd0e	a0234d98	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/02 18:40	upstream	eda809ae	79264ae3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/20 22:35	upstream	6a447b0e	04201c06	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/19 01:40	upstream	3644e2d2	04201c06	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/30 17:13	upstream	b6505459	76831598	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/24 01:31	upstream	418baf2c	878fb17a	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/23 14:13	upstream	418baf2c	0d27f508	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/23 06:02	upstream	68d3fa23	0d27f508	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/16 14:48	upstream	09162bc3	1bf9a662	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/14 03:11	upstream	9e6a39ea	1bf9a662	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/09 20:06	upstream	f8394f23	cba33199	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/04 19:17	upstream	4ef8451b	cba33199	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/26 21:21	upstream	3650b228	a7aac492	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/20 18:11	upstream	270315b8	ff4a3345	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/18 09:27	upstream	9d9af100	fea47c01	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/15 23:01	upstream	726eb70e	6e262c73	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/14 09:47	upstream	6ad4bf6e	fc7735a2	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/09 03:25	upstream	3d006ee4	92390980	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/01 22:35	upstream	fcadab74	9602ddf4	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/10 06:11	upstream	34d4ddd3	ac7ca78e	.config	log	report
ci2-upstream-kcsan-gce	2020/08/31 07:36	upstream	dcc5c6f0	d5a3ae1f	.config	log	report
ci2-upstream-kcsan-gce	2020/08/19 10:01	upstream	18445bf4	e1c29030	.config	log	report
ci2-upstream-kcsan-gce	2020/08/15 14:24	upstream	c9c9735c	5ce13532	.config	log	report
ci2-upstream-kcsan-gce	2020/08/15 01:05	upstream	a1d21081	5ce13532	.config	log	report
ci2-upstream-kcsan-gce	2020/08/07 15:05	upstream	86cfccb6	28ac5c9e	.config	log	report
ci2-upstream-kcsan-gce	2020/07/27 19:42	upstream	92ed3019	cb93dc6a	.config	log	report
ci2-upstream-kcsan-gce	2020/07/19 01:54	upstream	6cf7ccba	9c812472	.config	log	report
ci2-upstream-kcsan-gce	2020/07/06 20:55	upstream	5c82ec00	ef278c73	.config	log	report