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_inline
Status: moderation: reported on 2020/12/06 12:03
Reported-by: syzbot+ae21a27816f424fd3dda@syzkaller.appspotmail.com
First crash: 218d, last: 3d20h

Sample crash report:

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

read to 0xffffc9000b1b5018 of 8 bytes by task 8145 on cpu 0:
 add_echo_byte drivers/tty/n_tty.c:844 [inline]
 echo_char drivers/tty/n_tty.c:950 [inline]
 n_tty_receive_char_inline+0x42f/0x650 drivers/tty/n_tty.c:1421
 n_tty_receive_buf_standard drivers/tty/n_tty.c:1584 [inline]
 __receive_buf drivers/tty/n_tty.c:1647 [inline]
 n_tty_receive_buf_common+0x1892/0x1df0 drivers/tty/n_tty.c:1744
 n_tty_receive_buf+0x2b/0x40 drivers/tty/n_tty.c:1773
 tiocsti drivers/tty/tty_io.c:2200 [inline]
 tty_ioctl+0x928/0x1030 drivers/tty/tty_io.c:2574
 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 0xffffc9000b1b5018 of 8 bytes by task 6586 on cpu 1:
 echo_char drivers/tty/n_tty.c:845 [inline]
 n_tty_receive_char_inline+0x461/0x650 drivers/tty/n_tty.c:1421
 n_tty_receive_buf_standard drivers/tty/n_tty.c:1584 [inline]
 __receive_buf drivers/tty/n_tty.c:1647 [inline]
 n_tty_receive_buf_common+0x1892/0x1df0 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
 paste_selection+0x250/0x340 drivers/tty/vt/selection.c:408
 tioclinux+0xe5/0x450 drivers/tty/vt/vt.c:3164
 vt_ioctl+0xde0/0x20e0 drivers/tty/vt/vt_ioctl.c:823
 tty_ioctl+0xa34/0x1030 drivers/tty/tty_io.c:2658
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6586 Comm: syz-executor.4 Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (21):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci2-upstream-kcsan-gce	2021/01/21 11:52	upstream	75439bc4	d4f4eca5	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2021/01/10 04:48	upstream	2ff90100	2c1f2513	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/12/10 11:38	upstream	a2f5ea9e	2a55c22b	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/11/29 17:19	upstream	aae5ab85	a0092f9d	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/11/08 01:40	upstream	4429f14a	cba33199	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/11/07 14:56	upstream	659caaf6	cba33199	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/27 01:25	upstream	41ba50b0	8b3eaf58	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/10/02 09:06	upstream	fcadab74	9602ddf4	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/23 12:07	upstream	805c6d3c	287cd75a	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/16 20:28	upstream	5925fa68	77507d02	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/15 14:52	upstream	fc4f28bb	9e681632	.config	log	report	info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/12 09:18	upstream	e8878ab8	79fb24e2	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/06 11:16	upstream	dd9fb9bb	abf9ba4f	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/09/05 01:47	upstream	c70672d8	abf9ba4f	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/08/15 01:38	upstream	c9c9735c	5ce13532	.config	log	report		gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/07/21 14:59	upstream	4fa640dc	e562dd8a	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/07/07 20:25	upstream	bfe91da2	08fc4ef1	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/06/29 14:35	upstream	9ebcfadb	df01f6fc	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/06/29 11:11	upstream	9ebcfadb	3ff434cc	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/06/23 18:14	upstream	3e08a952	6930bbef	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org
ci2-upstream-kcsan-gce	2020/06/20 11:12	upstream	672f9255	c655ec77	.config	log	report		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org