KCSAN: data-race in n_tty_receive_char_inline / n_tty_receive_char

KCSAN: data-race in n_tty_receive_char_inline / n_tty_receive_char_special
Status: auto-closed as invalid on 2021/04/20 18:26
Reported-by: syzbot+fdab22f6fdfe878fbb0a@syzkaller.appspotmail.com
First crash: 303d, last: 35d

Sample crash report:

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

write to 0xffffc90002bc1018 of 8 bytes by task 10361 on cpu 0:
 echo_char drivers/tty/n_tty.c:840 [inline]
 eraser drivers/tty/n_tty.c:1039 [inline]
 n_tty_receive_char_special+0x142e/0x3ac0 drivers/tty/n_tty.c:1312
 n_tty_receive_buf_standard drivers/tty/n_tty.c:1580 [inline]
 __receive_buf drivers/tty/n_tty.c:1642 [inline]
 n_tty_receive_buf_common+0x191c/0x1e20 drivers/tty/n_tty.c:1739
 n_tty_receive_buf+0x2b/0x40 drivers/tty/n_tty.c:1768
 tiocsti drivers/tty/tty_io.c:2316 [inline]
 tty_ioctl+0x91a/0x10c0 drivers/tty/tty_io.c:2717
 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+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffc90002bc1018 of 8 bytes by task 300 on cpu 1:
 echo_char_raw drivers/tty/n_tty.c:840 [inline]
 finish_erasing drivers/tty/n_tty.c:957 [inline]
 n_tty_receive_char_inline+0x224/0x680 drivers/tty/n_tty.c:1412
 n_tty_receive_buf_standard drivers/tty/n_tty.c:1579 [inline]
 __receive_buf drivers/tty/n_tty.c:1642 [inline]
 n_tty_receive_buf_common+0x1893/0x1e20 drivers/tty/n_tty.c:1739
 n_tty_receive_buf2+0x2e/0x40 drivers/tty/n_tty.c:1774
 tty_ldisc_receive_buf+0x61/0xf0 drivers/tty/tty_buffer.c:461
 tty_port_default_receive_buf+0x54/0x80 drivers/tty/tty_port.c:38
 receive_buf drivers/tty/tty_buffer.c:481 [inline]
 flush_to_ldisc+0x1c5/0x2c0 drivers/tty/tty_buffer.c:533
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x616/0xa70 kernel/workqueue.c:2421
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 300 Comm: kworker/u4:2 Not tainted 5.12.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
==================================================================

Crashes (65):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/03/16 18:26	upstream	1df27313	fdb2bb2c	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_inline / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/07 14:33	upstream	a38fd874	c599ed12	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_inline / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/06 16:12	upstream	1e0d27fc	0655e081	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_inline / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/14 17:08	upstream	65f0d241	468dbb55	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/14 02:09	upstream	65f0d241	269d24e8	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/13 22:17	upstream	65f0d241	a945f0a3	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/13 11:40	upstream	e609571b	a945f0a3	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/06 15:19	upstream	9f1abbe9	fff20c29	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/26 04:04	upstream	5814bc2d	821e0b09	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/13 20:53	upstream	ec6f5e0e	8f160dd5	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/12 21:39	upstream	7b1b868e	bca53db9	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/12 02:40	upstream	7f376f19	bca53db9	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/11 11:38	upstream	33dc9614	ba24ffcd	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/11 00:13	upstream	9fca90cf	f900b48c	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/10 10:41	upstream	a2f5ea9e	c090b4da	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/09 10:09	upstream	a68a0262	99917735	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/08 00:06	upstream	cd796ed3	51a9082e	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/07 10:50	upstream	0477e928	f80ce148	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/06 21:35	upstream	8100a580	c521566d	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/06 10:07	upstream	7059c2c0	f12ba0c5	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/28 14:48	upstream	c84e1efa	3c7136c0	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/24 07:12	upstream	d5beb314	1ab681a4	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/23 04:27	upstream	68d3fa23	0d27f508	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/20 18:09	upstream	4d02da97	68068804	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/19 20:19	upstream	131ad0b6	0767f13f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/17 21:59	upstream	111e91a6	09323409	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/02 03:58	upstream	31f02006	8bc4594f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/02 03:39	upstream	31f02006	8bc4594f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/28 04:50	upstream	ed8780e3	96e03c1c	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/25 17:00	upstream	d7691390	a1839e81	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/25 16:59	upstream	d7691390	a1839e81	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/23 08:26	upstream	96485e44	4e740c00	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/18 08:58	upstream	9d9af100	fea47c01	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/28 09:41	upstream	a1b8638b	6bfdbe89	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/26 05:03	upstream	7c7ec322	4a006f63	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/12 19:04	upstream	729e3d09	21d289c2	.config	log	report
ci2-upstream-kcsan-gce	2020/09/08 18:14	upstream	f4d51dff	abf9ba4f	.config	log	report
ci2-upstream-kcsan-gce	2020/09/07 08:08	upstream	a8205e31	abf9ba4f	.config	log	report
ci2-upstream-kcsan-gce	2020/08/28 22:55	upstream	15bc20c6	d5a3ae1f	.config	log	report
ci2-upstream-kcsan-gce	2020/08/21 10:38	upstream	da2968ff	1d75fe45	.config	log	report
ci2-upstream-kcsan-gce	2020/08/19 18:14	upstream	18445bf4	db787902	.config	log	report
ci2-upstream-kcsan-gce	2020/08/18 09:12	upstream	06a4ec1d	5ce13532	.config	log	report
ci2-upstream-kcsan-gce	2020/08/10 16:06	upstream	fc80c51f	7adc7b65	.config	log	report
ci2-upstream-kcsan-gce	2020/08/10 01:46	upstream	9420f1ce	70301872	.config	log	report
ci2-upstream-kcsan-gce	2020/08/05 13:01	upstream	c0842fbc	b7129355	.config	log	report
ci2-upstream-kcsan-gce	2020/08/05 13:01	upstream	c0842fbc	b7129355	.config	log	report
ci2-upstream-kcsan-gce	2020/08/04 15:51	upstream	c0842fbc	80a06902	.config	log	report
ci2-upstream-kcsan-gce	2020/07/31 06:26	upstream	e2c46b57	8df85ed9	.config	log	report
ci2-upstream-kcsan-gce	2020/07/30 05:24	upstream	6ba1b005	233283a1	.config	log	report
ci2-upstream-kcsan-gce	2020/07/30 05:23	upstream	6ba1b005	233283a1	.config	log	report
ci2-upstream-kcsan-gce	2020/07/30 05:23	upstream	6ba1b005	233283a1	.config	log	report
ci2-upstream-kcsan-gce	2020/07/29 07:21	upstream	6ba1b005	19a8de55	.config	log	report
ci2-upstream-kcsan-gce	2020/07/28 21:58	upstream	6ba1b005	cb93dc6a	.config	log	report
ci2-upstream-kcsan-gce	2020/07/27 08:30	upstream	92ed3019	cb93dc6a	.config	log	report
ci2-upstream-kcsan-gce	2020/07/26 12:03	upstream	04300d66	51265195	.config	log	report
ci2-upstream-kcsan-gce	2020/07/24 20:32	upstream	f37e99ac	554af388	.config	log	report
ci2-upstream-kcsan-gce	2020/07/20 17:14	upstream	5714ee50	8caeeeb7	.config	log	report
ci2-upstream-kcsan-gce	2020/07/20 17:04	upstream	5714ee50	8caeeeb7	.config	log	report
ci2-upstream-kcsan-gce	2020/07/20 17:03	upstream	5714ee50	8caeeeb7	.config	log	report
ci2-upstream-kcsan-gce	2020/07/20 16:55	upstream	5714ee50	8caeeeb7	.config	log	report
ci2-upstream-kcsan-gce	2020/07/07 18:26	upstream	bfe91da2	42723355	.config	log	report
ci2-upstream-kcsan-gce	2020/07/06 11:03	upstream	dcb7fd82	ac5a135b	.config	log	report
ci2-upstream-kcsan-gce	2020/07/06 11:01	upstream	dcb7fd82	ac5a135b	.config	log	report
ci2-upstream-kcsan-gce	2020/07/04 14:31	upstream	35e884f8	4f739670	.config	log	report
ci2-upstream-kcsan-gce	2020/06/21 16:32	upstream	64677779	4f2acff9	.config	log	report