KCSAN: data-race in capable_wrt_inode_uidgid / mm_update_next

KCSAN: data-race in capable_wrt_inode_uidgid / mm_update_next_owner (2)
Status: auto-closed as invalid on 2020/11/04 12:23
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 396d, last: 383d

similar bugs (3):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in capable_wrt_inode_uidgid / mm_update_next_owner (4)	7	139d	199d	0/22	auto-closed as invalid on 2021/07/06 03:43
upstream	KCSAN: data-race in capable_wrt_inode_uidgid / mm_update_next_owner (3)	1	306d	306d	0/22	auto-closed as invalid on 2021/01/20 08:48
upstream	KCSAN: data-race in capable_wrt_inode_uidgid / mm_update_next_owner	1	438d	438d	0/22	auto-closed as invalid on 2020/09/10 17:38

Sample crash report:

==================================================================
BUG: KCSAN: data-race in capable_wrt_inode_uidgid / mm_update_next_owner

write to 0xffff888094134064 of 4 bytes by task 20957 on cpu 0:
 ns_capable_common kernel/capability.c:377 [inline]
 ns_capable kernel/capability.c:396 [inline]
 capable_wrt_inode_uidgid+0xa0/0x130 kernel/capability.c:506
 generic_permission+0x19b/0x3e0 fs/namei.c:381
 do_inode_permission fs/namei.c:405 [inline]
 inode_permission+0x6c/0x330 fs/namei.c:463
 may_open+0x19f/0x2e0 fs/namei.c:2874
 do_open fs/namei.c:3249 [inline]
 path_openat+0x17b0/0x20a0 fs/namei.c:3368
 do_filp_open+0xbd/0x1d0 fs/namei.c:3395
 do_sys_openat2+0x33b/0x500 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

read to 0xffff888094134064 of 4 bytes by task 20959 on cpu 1:
 mm_update_next_owner+0x1d9/0x4a0 kernel/exit.c:387
 exit_mm+0x2c0/0x330 kernel/exit.c:482
 do_exit+0x40f/0x16c0 kernel/exit.c:793
 do_group_exit+0x17a/0x180 kernel/exit.c:903
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:914
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:912
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:912
 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: 20959 Comm: syz-executor.0 Not tainted 5.9.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/09/30 12:17	upstream	02de58b24d2e	8516f6d3	.config	log	report			info
ci2-upstream-kcsan-gce	2020/09/17 08:57	upstream	5925fa68fe82	8247808b	.config	log	report			info