KCSAN: data-race in exit_signals / task_dump

KCSAN: data-race in exit_signals / task_dump_owner (4)
Status: auto-closed as invalid on 2021/01/31 10:55
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 217d, last: 217d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in exit_signals / task_dump_owner (2)	5	411d	519d	0/22	closed as invalid on 2020/06/18 14:24
upstream	KCSAN: data-race in exit_signals / task_dump_owner (5)	22	59d	142d	0/22	auto-closed as invalid on 2021/07/08 00:56
upstream	KCSAN: data-race in exit_signals / task_dump_owner	4	594d	628d	0/22	auto-closed as invalid on 2020/02/24 01:47
upstream	KCSAN: data-race in exit_signals / task_dump_owner (3)	13	255d	237d	0/22	auto-closed as invalid on 2020/12/24 05:44

Sample crash report:

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

read-write to 0xffff8880320cd02c of 4 bytes by task 31905 on cpu 1:
 exit_signals+0x102/0x530 kernel/signal.c:2862
 do_exit+0x15d/0x1630 kernel/exit.c:779
 do_group_exit+0x16f/0x170 kernel/exit.c:920
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:931
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:929
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:929
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880320cd02c of 4 bytes by task 31913 on cpu 0:
 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
 open_last_lookups fs/namei.c:3146 [inline]
 path_openat+0x48e/0x20a0 fs/namei.c:3368
 do_filp_open+0xbd/0x1d0 fs/namei.c:3398
 do_sys_openat2+0xa3/0x240 fs/open.c:1172
 do_sys_open fs/open.c:1188 [inline]
 __do_sys_open fs/open.c:1196 [inline]
 __se_sys_open fs/open.c:1192 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1192
 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: 31913 Comm: syz-executor.1 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/12/27 10:48	upstream	f838f8d2b694	821e0b09	.config	log	report			info