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: moderation: reported on 2020/12/07 11:26
Reported-by: syzbot+c8b476f28b4240b598d0@syzkaller.appspotmail.com
First crash: 214d, last: 3h11m

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	257d	299d	0/19	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	448d	448d	0/19	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

read to 0xffffc90003a45018 of 8 bytes by task 17170 on cpu 0:
 add_echo_byte drivers/tty/n_tty.c:844 [inline]
 echo_char_raw drivers/tty/n_tty.c:924 [inline]
 eraser drivers/tty/n_tty.c:1080 [inline]
 n_tty_receive_char_special+0x1648/0x3860 drivers/tty/n_tty.c:1317
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1611 [inline]
 __receive_buf drivers/tty/n_tty.c:1645 [inline]
 n_tty_receive_buf_common+0xe2b/0x1df0 drivers/tty/n_tty.c:1744
 n_tty_receive_buf+0x2b/0x40 drivers/tty/n_tty.c:1773
 tiocsti drivers/tty/tty_io.c:2203 [inline]
 tty_ioctl+0x928/0x1030 drivers/tty/tty_io.c:2577
 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+0x44/0xa9

read-write to 0xffffc90003a45018 of 8 bytes by task 3179 on cpu 1:
 add_echo_byte drivers/tty/n_tty.c:846 [inline]
 echo_char_raw drivers/tty/n_tty.c:924 [inline]
 eraser drivers/tty/n_tty.c:1081 [inline]
 n_tty_receive_char_special+0x16aa/0x3860 drivers/tty/n_tty.c:1317
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1611 [inline]
 __receive_buf drivers/tty/n_tty.c:1645 [inline]
 n_tty_receive_buf_common+0xe2b/0x1df0 drivers/tty/n_tty.c:1744
 n_tty_receive_buf2+0x2e/0x40 drivers/tty/n_tty.c:1779
 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+0x1c5/0x2b0 drivers/tty/tty_buffer.c:533
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x64a/0xaa0 kernel/workqueue.c:2421
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3179 Comm: kworker/u4:4 Not tainted 5.11.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc

==================================================================

Crashes (63):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci2-upstream-kcsan-gce	2021/01/27 10:38	upstream	2ab38c17	a0ebf917	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/26 22:42	upstream	13391c60	55a7d4df	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/26 08:20	upstream	f8ad8187	52e37319	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/24 01:31	upstream	e1ae4b0b	52e37319	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/23 14:33	upstream	fe75a218	52e37319	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/22 19:53	upstream	83d09ad4	52e37319	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/21 15:37	upstream	9791581c	d4f4eca5	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/20 23:27	upstream	75439bc4	d4f4eca5	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/20 09:18	upstream	45dfb8a5	d4f4eca5	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/18 23:53	upstream	1e2a199f	63631df1	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/18 19:50	upstream	19c329f6	63631df1	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/16 21:09	upstream	54c6247d	65a7a854	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/14 21:04	upstream	65f0d241	468dbb55	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/13 14:55	upstream	e609571b	a945f0a3	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/11 11:15	upstream	7c53f6b6	2c1f2513	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/11 02:36	upstream	0653161f	2c1f2513	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/06 16:50	upstream	9f1abbe9	fff20c29	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/05 12:59	upstream	36bbbd0e	a0234d98	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/05 02:55	upstream	36bbbd0e	2a28ff1f	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/04 06:05	upstream	e71ba945	79264ae3	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/30 17:50	upstream	139711f0	ecb8c012	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/29 11:08	upstream	dea8dcf2	8259d56c	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/28 08:09	upstream	5c8fe583	2242f77f	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/27 02:18	upstream	f838f8d2	821e0b09	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/24 00:34	upstream	58cf05f5	c2c1d1dd	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/23 10:22	upstream	614cb589	04201c06	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/21 08:51	upstream	e37b12e4	04201c06	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/20 00:13	upstream	467f8165	04201c06	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/15 21:08	upstream	148842c9	f213e07e	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/14 06:09	upstream	ec6f5e0e	8f160dd5	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/13 09:16	upstream	6bff9bb8	bca53db9	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/13 00:24	upstream	7b1b868e	bca53db9	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/12 04:26	upstream	7f376f19	bca53db9	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/11 00:18	upstream	9fca90cf	f900b48c	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/09 00:08	upstream	7d8761ba	40cc414d	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/11/27 22:05	upstream	85a2c56c	486f93ef	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/11/25 23:45	upstream	fa02fcd9	3f581b43	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/11/14 18:06	upstream	f01c30de	1bf9a662	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/11/07 03:07	upstream	bf3e7628	cba33199	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/31 22:50	upstream	5fc6b075	8bc4594f	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/24 10:57	upstream	f11901ed	2bb6666c	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/23 13:55	upstream	f9893351	4e740c00	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/22 11:03	upstream	f804b315	be6b1582	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/24 14:48	upstream	c9c9e6a4	54289b08	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/20 03:53	upstream	325d0eab	53ce8104	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/17 04:15	upstream	5925fa68	8247808b	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/14 04:11	upstream	84b13499	2d3cdd63	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/02 13:03	upstream	b765a32a	abf9ba4f	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/08/30 02:17	upstream	4d41ead6	d5a3ae1f	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/08/28 01:28	upstream	15bc20c6	816e0689	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/08/24 14:56	upstream	d012a719	67b599d1	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/08/23 19:40	upstream	cb957121	a6d5f3ad	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/08/23 12:34	upstream	c3d8f220	a6d5f3ad	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/08/22 13:52	upstream	f873db9a	6436ce4b	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/08/19 08:07	upstream	18445bf4	e1c29030	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/08/07 08:02	upstream	d6efb3ac	cb436c69	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/07/30 19:47	upstream	83bdc727	b0947553	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/07/26 23:34	upstream	1ada9010	51265195	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/07/16 10:22	upstream	994e99a9	ada108d0	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/07/08 03:44	upstream	aa27b32b	08fc4ef1	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/07/07 06:11	upstream	5c82ec00	ef278c73	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/06/27 02:51	upstream	1590a2e1	ffec44b5	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org