KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char

KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special (3)
Status: auto-closed as invalid on 2021/08/13 21:23
Reported-by: syzbot+c8b476f28b4240b598d0@syzkaller.appspotmail.com
First crash: 452d, last: 74d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special (2)				5	495d	537d	0/22	auto-closed as invalid on 2020/06/19 11:58
upstream	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special				1	686d	686d	0/22	closed as invalid on 2019/11/19 13:54

Sample crash report:

==================================================================
BUG: KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special

write to 0xffffc9000f4d5018 of 8 bytes by task 15578 on cpu 1:
 echo_char_raw drivers/tty/n_tty.c:841 [inline]
 eraser drivers/tty/n_tty.c:1076 [inline]
 n_tty_receive_char_special+0x1797/0x3ac0 drivers/tty/n_tty.c:1313
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1607 [inline]
 __receive_buf drivers/tty/n_tty.c:1641 [inline]
 n_tty_receive_buf_common+0xe0c/0x1e20 drivers/tty/n_tty.c:1740
 n_tty_receive_buf+0x2b/0x40 drivers/tty/n_tty.c:1769
 tiocsti drivers/tty/tty_io.c:2315 [inline]
 tty_ioctl+0x968/0x1120 drivers/tty/tty_io.c:2721
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffc9000f4d5018 of 8 bytes by task 8 on cpu 0:
 echo_char_raw drivers/tty/n_tty.c:841 [inline]
 eraser drivers/tty/n_tty.c:1078 [inline]
 n_tty_receive_char_special+0x17f6/0x3ac0 drivers/tty/n_tty.c:1313
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1607 [inline]
 __receive_buf drivers/tty/n_tty.c:1641 [inline]
 n_tty_receive_buf_common+0xe0c/0x1e20 drivers/tty/n_tty.c:1740
 n_tty_receive_buf2+0x2e/0x40 drivers/tty/n_tty.c:1775
 tty_ldisc_receive_buf+0x5b/0xf0 drivers/tty/tty_buffer.c:461
 tty_port_default_receive_buf+0x54/0x80 drivers/tty/tty_port.c:39
 receive_buf drivers/tty/tty_buffer.c:481 [inline]
 flush_to_ldisc+0x1c5/0x2c0 drivers/tty/tty_buffer.c:533
 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2276
 worker_thread+0x636/0xae0 kernel/workqueue.c:2422
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

value changed: 0x00000000000005d9 -> 0x00000000000006b7

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8 Comm: kworker/u4:0 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
==================================================================

Crashes (191):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/07/09 21:22	upstream	3dbdb38e2869	8f5a7b8c	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/07/09 15:51	upstream	3dbdb38e2869	281e815f	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/07/09 06:50	upstream	3dbdb38e2869	1b20171a	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/07/07 19:09	upstream	3dbdb38e2869	95793bce	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/07/07 07:46	upstream	3dbdb38e2869	4846d5c1	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/07/06 07:57	upstream	3dbdb38e2869	6c4484eb	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/07/04 05:46	upstream	3dbdb38e2869	55aa55c2	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/07/02 12:44	upstream	3dbdb38e2869	658ebc66	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/07/01 23:22	upstream	e058a84bfddc	658ebc66	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/07/01 13:36	upstream	dbe69e433722	658ebc66	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/07/01 03:57	upstream	df04fbe8680b	38a885d1	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/30 08:52	upstream	007b350a5875	84fd4c77	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/29 20:04	upstream	c54b245d0118	a4fccb01	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/29 01:52	upstream	122fa8c58831	9d2ab5df	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/28 06:24	upstream	b4b27b9eed8e	9d2ab5df	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/27 00:40	upstream	625acffd7ae2	9d2ab5df	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/22 19:43	upstream	0c18f29aae7c	aba2b2fb	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/18 07:31	upstream	fd0aa1a4567d	aba2b2fb	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/17 13:28	upstream	70585216fe77	aba2b2fb	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/15 11:48	upstream	009c9aa5be65	8022d7e3	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/14 10:04	upstream	009c9aa5be65	1ba81399	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/14 01:03	upstream	e4e453434a19	1ba81399	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/13 20:25	upstream	8ecfa36cd4db	1ba81399	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/12 11:52	upstream	ad347abe4a98	1ba81399	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/11 10:33	upstream	06af8679449d	1ba81399	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/10 01:13	upstream	cd1245d75ce9	1ba81399	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/09 20:47	upstream	368094df48e6	84fe5d96	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/08 02:30	upstream	614124bea77e	b718257f	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/07 14:44	upstream	614124bea77e	e59537be	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/06 21:27	upstream	decad3e1d1ed	500c2339	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/06 00:48	upstream	f5b6eb1e0182	500c2339	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/05 11:01	upstream	9d32fa5d74b1	500c2339	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/04 10:27	upstream	f88cd3fb9df2	966a236b	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/02 21:29	upstream	324c92e5e0ee	0740de69	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/02 07:45	upstream	231bc5390667	0740de69	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/02 05:00	upstream	231bc5390667	032639db	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/06/01 17:52	upstream	c2131f7e73c9	032639db	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/05/31 10:16	upstream	8124c8a6b353	032639db	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/05/29 19:53	upstream	f956cb99b938	325a8dab	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/05/27 12:30	upstream	d7c5303fbc8a	858ea628	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/05/27 03:26	upstream	7ac3a1c1ae51	858ea628	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/05/26 08:44	upstream	ad9f25d33860	93d3a9f6	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/16 21:09	upstream	54c6247d06f1	65a7a854	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/27 22:05	upstream	85a2c56cb445	486f93ef	.config	log	report	info
ci2-upstream-kcsan-gce	2020/06/27 02:51	upstream	1590a2e1c681	ffec44b5	.config	log	report