KCSAN: data-race in exit_signals / task_dump

KCSAN: data-race in exit_signals / task_dump_owner (3)
Status: auto-closed as invalid on 2020/12/24 05:44
Reported-by: syzbot+fef1fca3947c120bc9e0@syzkaller.appspotmail.com
First crash: 394d, last: 253d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in exit_signals / task_dump_owner (2)	5	409d	517d	0/22	closed as invalid on 2020/06/18 14:24
upstream	KCSAN: data-race in exit_signals / task_dump_owner (4)	1	214d	214d	0/22	auto-closed as invalid on 2021/01/31 10:55
upstream	KCSAN: data-race in exit_signals / task_dump_owner (5)	22	57d	140d	0/22	auto-closed as invalid on 2021/07/08 00:56
upstream	KCSAN: data-race in exit_signals / task_dump_owner	4	592d	625d	0/22	auto-closed as invalid on 2020/02/24 01:47

Sample crash report:

==================================================================
BUG: KCSAN: data-race in exit_signals / task_dump_owner

read-write to 0xffff888020807024 of 4 bytes by task 11213 on cpu 0:
 exit_signals+0x108/0x530 kernel/signal.c:2846
 do_exit+0x158/0x15a0 kernel/exit.c:765
 do_group_exit+0x16f/0x170 kernel/exit.c:906
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:917
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:915
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:915
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888020807024 of 4 bytes by task 11216 on cpu 1:
 task_dump_owner+0x2b/0x1b0 fs/proc/base.c:1823
 pid_update_inode fs/proc/base.c:1965 [inline]
 pid_revalidate+0x69/0x110 fs/proc/base.c:1988
 lookup_fast+0x208/0x370 fs/namei.c:768
 walk_component+0x5c/0x350 fs/namei.c:1857
 link_path_walk+0x451/0x710 fs/namei.c:2180
 path_openat+0x19f/0x20a0 fs/namei.c:3365
 do_filp_open+0xbd/0x1d0 fs/namei.c:3396
 do_sys_openat2+0xa3/0x240 fs/open.c:1168
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_open fs/open.c:1192 [inline]
 __se_sys_open fs/open.c:1188 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1188
 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: 11216 Comm: syz-executor.5 Not tainted 5.10.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (13):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info
ci2-upstream-kcsan-gce	2020/11/19 05:43	upstream	c2e7554e1b85	0767f13f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/18 18:11	upstream	0fa8ee0d9ab9	0767f13f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/06 16:38	upstream	521b619acdc8	cba33199	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/27 00:30	upstream	41ba50b0572e	8b3eaf58	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/24 21:22	upstream	171d4ff79f96	54289b08	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/24 12:32	upstream	c9c9e6a49f89	54289b08	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/02 11:11	upstream	b765a32a2e91	abf9ba4f	.config	log	report
ci2-upstream-kcsan-gce	2020/08/27 07:41	upstream	15bc20c6af4c	816e0689	.config	log	report
ci2-upstream-kcsan-gce	2020/08/16 00:24	upstream	410520d07f5c	5ce13532	.config	log	report
ci2-upstream-kcsan-gce	2020/08/09 11:03	upstream	06a81c1c7db9	f721e4a0	.config	log	report
ci2-upstream-kcsan-gce	2020/07/08 20:30	upstream	63e1968a2c87	9f9845eb	.config	log	report
ci2-upstream-kcsan-gce	2020/07/02 14:01	upstream	cd77006e01b3	f30c14bf	.config	log	report
ci2-upstream-kcsan-gce	2020/06/30 18:11	upstream	7c30b859a947	917afeaa	.config	log	report