KCSAN: data-race in snd_rawmidi_transmit / snd_rawmidi

KCSAN: data-race in snd_rawmidi_transmit / snd_rawmidi_write
Status: fixed on 2021/03/10 01:49
Reported-by: syzbot+a23a6f1215c84756577c@syzkaller.appspotmail.com
Fix commit: 88a06d6fd6b3 ALSA: rawmidi: Access runtime->avail always in spinlock
First crash: 528d, last: 303d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in snd_rawmidi_transmit / snd_rawmidi_write (2)				4	260d	268d	0/22	auto-closed as invalid on 2021/04/23 19:29

Sample crash report:

==================================================================
BUG: KCSAN: data-race in snd_rawmidi_transmit / snd_rawmidi_write

write to 0xffff8880289c07b8 of 8 bytes by task 2048 on cpu 1:
 __snd_rawmidi_transmit_ack sound/core/rawmidi.c:1267 [inline]
 snd_rawmidi_transmit+0x2b8/0x3b0 sound/core/rawmidi.c:1326
 snd_vmidi_output_work+0xf1/0x200 sound/core/seq/seq_virmidi.c:144
 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:296

read to 0xffff8880289c07b8 of 8 bytes by task 27017 on cpu 0:
 snd_rawmidi_write+0x5ef/0x720 sound/core/rawmidi.c:1489
 vfs_write+0x21a/0x7e0 fs/read_write.c:603
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 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: 0 PID: 27017 Comm: syz-executor.4 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (232):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/02/04 19:55	upstream	61556703b610	42b90a7c	.config	log	report	info	KCSAN: data-race in snd_rawmidi_transmit / snd_rawmidi_write
ci2-upstream-kcsan-gce	2021/01/07 22:36	upstream	f5e6c330254a	c104d4a3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/16 02:57	upstream	d635a69dd498	f213e07e	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/15 20:27	upstream	148842c98a24	f213e07e	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/15 13:32	upstream	148842c98a24	97183ed7	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/14 21:41	upstream	fab0fca1da5c	97183ed7	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/14 09:39	upstream	2c85ebc57b3e	b22a7ec3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/13 09:53	upstream	6bff9bb8a292	bca53db9	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/11 05:29	upstream	9fca90cf2892	f900b48c	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/06 11:24	upstream	7059c2c00a21	f12ba0c5	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/03 12:53	upstream	34816d20f173	59ad4022	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/28 04:03	upstream	c84e1efae022	486f93ef	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/25 23:49	upstream	fa02fcd94b0c	3f581b43	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/19 16:43	upstream	c2e7554e1b85	0767f13f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/18 18:37	upstream	0fa8ee0d9ab9	0767f13f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/18 14:00	upstream	0fa8ee0d9ab9	09323409	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/18 01:45	upstream	111e91a6df50	09323409	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/17 15:44	upstream	9c87c9f41245	bd2a760b	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/16 19:11	upstream	09162bc32c88	1bf9a662	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/15 07:24	upstream	e28c0d7c92c8	1bf9a662	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/14 18:04	upstream	f01c30de86f1	1bf9a662	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/14 10:04	upstream	9e6a39eae450	1bf9a662	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/08 05:08	upstream	4429f14aeea9	cba33199	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/06 01:33	upstream	521b619acdc8	cba33199	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/05 15:32	upstream	4ef8451b3326	cba33199	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/01 22:03	upstream	31f020064f9d	8bc4594f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/01 08:03	upstream	c2dc4c073fb7	8bc4594f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/31 00:42	upstream	f5d808567a51	18e33098	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/29 22:02	upstream	23859ae44402	a0c7169a	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/27 20:14	upstream	4525c8781ec0	94942294	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/27 09:29	upstream	41ba50b0572e	8b3eaf58	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/20 16:53	upstream	270315b8235e	ff4a3345	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/20 02:43	upstream	bbe85027ce80	ff4a3345	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/19 17:00	upstream	7cf726a59435	ff4a3345	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/19 00:35	upstream	9453b2d4694c	fea47c01	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/18 04:20	upstream	9d9af1007bc0	fea47c01	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/16 23:42	upstream	54a4c789ca80	6e262c73	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/16 11:31	upstream	9ff9b0d392ea	6e262c73	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/16 04:05	upstream	726eb70e0d34	6e262c73	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/15 05:08	upstream	3e4fb4346c78	fc7735a2	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/11 21:41	upstream	3dd0130f2430	4a77ae0b	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/11 02:30	upstream	da690031a5d6	4a77ae0b	.config	log	report	info
ci2-upstream-kcsan-gce	2020/08/12 16:13	upstream	fb893de323e2	0d7bd2e0	.config	log	report
ci2-upstream-kcsan-gce	2020/06/24 19:57	upstream	26e122e97a3d	9d60b18e	.config	log	report