KCSAN: data-race in n_tty_receive_buf_common / n_tty_receive_char

KCSAN: data-race in n_tty_receive_buf_common / n_tty_receive_char_special
Status: moderation: reported on 2019/12/12 22:35
Reported-by: syzbot+6636788b7ec318c30f07@syzkaller.appspotmail.com
First crash: 362d, last: 6h44m

Sample crash report:

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

read-write to 0xffffc900045b5018 of 8 bytes by task 8332 on cpu 0:
 add_echo_byte drivers/tty/n_tty.c:845 [inline]
 echo_char drivers/tty/n_tty.c:948 [inline]
 eraser drivers/tty/n_tty.c:1043 [inline]
 n_tty_receive_char_special+0x111e/0x3860 drivers/tty/n_tty.c:1316
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1610 [inline]
 __receive_buf drivers/tty/n_tty.c:1644 [inline]
 n_tty_receive_buf_common+0xe2b/0x1df0 drivers/tty/n_tty.c:1742
 n_tty_receive_buf+0x2b/0x40 drivers/tty/n_tty.c:1771
 tiocsti drivers/tty/tty_io.c:2196 [inline]
 tty_ioctl+0x8e4/0xfd0 drivers/tty/tty_io.c:2570
 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 to 0xffffc900045b5018 of 8 bytes by task 2849 on cpu 1:
 commit_echoes drivers/tty/n_tty.c:779 [inline]
 n_tty_receive_char_fast drivers/tty/n_tty.c:1449 [inline]
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1609 [inline]
 __receive_buf drivers/tty/n_tty.c:1644 [inline]
 n_tty_receive_buf_common+0x13a6/0x1df0 drivers/tty/n_tty.c:1742
 n_tty_receive_buf2+0x2e/0x40 drivers/tty/n_tty.c:1777
 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:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1ff/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: 2849 Comm: kworker/u4:7 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
==================================================================

Crashes (594):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci2-upstream-kcsan-gce	2020/10/21 03:37	upstream	c4d6fe73	ff4a3345	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/19 09:45	upstream	7cf726a5	ff4a3345	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/19 08:00	upstream	7cf726a5	fea47c01	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/18 18:19	upstream	9453b2d4	fea47c01	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/18 09:36	upstream	9d9af100	fea47c01	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/17 12:45	upstream	071a0578	fea47c01	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/16 09:46	upstream	9ff9b0d3	6e262c73	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/15 20:46	upstream	726eb70e	6e262c73	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/15 18:22	upstream	726eb70e	63869021	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/15 08:17	upstream	3e4fb434	63869021	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/15 01:34	upstream	3e4fb434	fc7735a2	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/14 10:38	upstream	b5fc7a89	fc7735a2	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/13 22:45	upstream	6ad4bf6e	fc7735a2	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/13 01:24	upstream	1e6d1d96	d32b0bbf	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/12 09:06	upstream	bbf5c979	4a77ae0b	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/11 21:52	upstream	3dd0130f	4a77ae0b	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/11 00:20	upstream	da690031	4a77ae0b	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/10 10:31	upstream	6f2f486d	b74c49a6	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/09 22:22	upstream	8a5f78d9	93817d89	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/09 11:03	upstream	583090b1	fa79ed2a	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/08 20:19	upstream	3d006ee4	92390980	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/08 10:41	upstream	c85fb28b	92390980	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/06 20:56	upstream	c85fb28b	1880b4a9	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/05 21:00	upstream	7575fdda	1880b4a9	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/05 13:24	upstream	549738f1	1880b4a9	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/05 00:54	upstream	549738f1	5ef9c291	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/04 09:08	upstream	22fbc037	5ef9c291	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/03 21:49	upstream	22fbc037	1a3f9408	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/03 16:45	upstream	d3d45f82	1a3f9408	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/03 03:41	upstream	d3d45f82	2653fa43	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/02 13:56	upstream	472e5b05	062c9832	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/01 21:19	upstream	fcadab74	9602ddf4	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/01 08:30	upstream	60e72093	4103fce0	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/30 22:05	upstream	60e72093	a9767fb2	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/30 18:43	upstream	02de58b2	a9767fb2	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/30 07:17	upstream	02de58b2	8516f6d3	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/30 05:36	upstream	02de58b2	5abc3f1a	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/29 14:37	upstream	fb0155a0	5abc3f1a	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/28 23:45	upstream	fb0155a0	1b88c6d5	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/28 08:10	upstream	a1b8638b	6bfdbe89	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/28 02:59	upstream	a1b8638b	5dd8aee8	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/27 13:19	upstream	a1bffa48	5dd8aee8	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/26 23:35	upstream	eeddbe68	5dd8aee8	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/26 18:58	upstream	eeddbe68	2d5ea0cb	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2019/12/12 17:49	https://github.com/google/ktsan.git kcsan	ef798c30	08003f64	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2019/12/12 07:06	https://github.com/google/ktsan.git kcsan	ef798c30	d973f528	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2019/10/25 06:55	https://github.com/google/ktsan.git kcsan	05f22368	d01bb02a	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org