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: 292d, last: 2d19h

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	334d	376d	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	526d	526d	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 0xffffc90000f09000 of 8 bytes by task 8044 on cpu 1:
 put_tty_queue drivers/tty/n_tty.c:315 [inline]
 n_tty_receive_char_special+0x39ce/0x3ac0 drivers/tty/n_tty.c:1373
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1606 [inline]
 __receive_buf drivers/tty/n_tty.c:1640 [inline]
 n_tty_receive_buf_common+0xe0c/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 0xffffc90000f09000 of 8 bytes by task 16671 on cpu 0:
 n_tty_receive_char_special+0x39da/0x3ac0 drivers/tty/n_tty.c:1374
 n_tty_receive_buf_fast drivers/tty/n_tty.c:1606 [inline]
 __receive_buf drivers/tty/n_tty.c:1640 [inline]
 n_tty_receive_buf_common+0xe0c/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
 paste_selection+0x250/0x340 drivers/tty/vt/selection.c:408
 tioclinux+0xe5/0x450 drivers/tty/vt/vt.c:3163
 vt_ioctl+0x26e/0x1ea0 drivers/tty/vt/vt_ioctl.c:723
 tty_ioctl+0xa2c/0x10c0 drivers/tty/tty_io.c:2801
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16671 Comm: syz-executor.0 Not tainted 5.12.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (98):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/04/12 12:30	upstream	d434405a	6a81331a	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/04/10 05:07	upstream	4e04e751	6a81331a	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/04/07 20:43	upstream	3a229812	6a81331a	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/28 20:18	upstream	36a14638	a8529b82	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/25 10:25	upstream	e1381380	6a383ecf	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/22 18:27	upstream	0d02ec6b	8092f30d	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/22 06:30	upstream	5ee96fa9	bea32f74	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/20 23:07	upstream	812da4d3	17810eae	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/20 00:38	upstream	8b12a62a	3d01c4de	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/19 07:02	upstream	bf152b0b	380dcc3e	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/16 22:34	upstream	1df27313	fdb2bb2c	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/15 00:29	upstream	75013c6c	cc1cff8f	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/12 23:32	upstream	f296bfd5	429d8a6b	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/10 08:59	upstream	05a59d79	26967e35	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/07 22:44	upstream	144c79ef	09fbf400	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/07 21:32	upstream	a38fd874	09fbf400	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/06 02:35	upstream	280d542f	4a024a9b	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/03/04 03:10	upstream	f69d02e3	06ed56cd	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/24 18:28	upstream	c03c21ba	fcc6d71b	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/22 17:06	upstream	31caf8b2	c26fb06b	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/17 21:20	upstream	f40ddce8	14052202	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/15 03:15	upstream	f40ddce8	98682e5e	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/14 15:12	upstream	358fecee	98682e5e	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/11 22:53	upstream	291009f6	a5f86b15	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/11 01:03	upstream	291009f6	a52ee10a	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/08 22:41	upstream	e0756cfc	2bd9619f	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/08 00:14	upstream	b75dba7f	2ce644fc	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/06 03:38	upstream	1e0d27fc	23a562df	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/02 22:59	upstream	3aaf0a27	624dad51	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/01 21:16	upstream	88bb507a	e6b95f32	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/02/01 13:20	upstream	1048ba83	e6b95f32	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/30 00:04	upstream	bec4c296	fc9fd31e	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/29 10:15	upstream	bec4c296	6593fd32	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/29 00:43	upstream	e5ff2cb9	7df34f59	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/28 07:27	upstream	76c057c8	eefc07f2	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/27 10:38	upstream	2ab38c17	a0ebf917	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/26 22:42	upstream	13391c60	55a7d4df	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/26 08:20	upstream	f8ad8187	52e37319	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/24 01:31	upstream	e1ae4b0b	52e37319	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/23 14:33	upstream	fe75a218	52e37319	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/22 19:53	upstream	83d09ad4	52e37319	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/21 15:37	upstream	9791581c	d4f4eca5	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/20 23:27	upstream	75439bc4	d4f4eca5	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/20 09:18	upstream	45dfb8a5	d4f4eca5	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/18 23:53	upstream	1e2a199f	63631df1	.config	log	report	info	KCSAN: data-race in n_tty_receive_char_special / n_tty_receive_char_special
ci2-upstream-kcsan-gce	2021/01/18 19:50	upstream	19c329f6	63631df1	.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	54c6247d	65a7a854	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/14 21:04	upstream	65f0d241	468dbb55	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/13 14:55	upstream	e609571b	a945f0a3	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/11 11:15	upstream	7c53f6b6	2c1f2513	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/27 22:05	upstream	85a2c56c	486f93ef	.config	log	report	info
ci2-upstream-kcsan-gce	2020/07/30 19:47	upstream	83bdc727	b0947553	.config	log	report
ci2-upstream-kcsan-gce	2020/07/26 23:34	upstream	1ada9010	51265195	.config	log	report
ci2-upstream-kcsan-gce	2020/07/16 10:22	upstream	994e99a9	ada108d0	.config	log	report
ci2-upstream-kcsan-gce	2020/07/08 03:44	upstream	aa27b32b	08fc4ef1	.config	log	report
ci2-upstream-kcsan-gce	2020/07/07 06:11	upstream	5c82ec00	ef278c73	.config	log	report
ci2-upstream-kcsan-gce	2020/06/27 02:51	upstream	1590a2e1	ffec44b5	.config	log	report