KCSAN: data-race in step_into / vfs

KCSAN: data-race in step_into / vfs_rename (6)
Status: auto-closed as invalid on 2021/10/14 13:13
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 89d, last: 89d

similar bugs (5):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in step_into / vfs_rename (5)	1	133d	133d	0/22	auto-closed as invalid on 2021/08/31 22:21
upstream	KCSAN: data-race in step_into / vfs_rename	2	540d	589d	0/22	closed as invalid on 2020/06/18 14:24
upstream	KCSAN: data-race in step_into / vfs_rename (2)	1	531d	531d	0/22	auto-closed as invalid on 2020/07/29 00:43
upstream	KCSAN: data-race in step_into / vfs_rename (3)	3	413d	446d	0/22	auto-closed as invalid on 2020/11/24 01:44
upstream	KCSAN: data-race in step_into / vfs_rename (4)	1	341d	341d	0/22	auto-closed as invalid on 2021/02/04 02:28

Sample crash report:

==================================================================
BUG: KCSAN: data-race in step_into / vfs_rename

write to 0xffff88812f1a0e40 of 4 bytes by task 20518 on cpu 1:
 dont_mount include/linux/dcache.h:358 [inline]
 vfs_rename+0xbda/0xe20 fs/namei.c:4638
 do_renameat2+0x6d7/0xa30 fs/namei.c:4779
 __do_sys_rename fs/namei.c:4825 [inline]
 __se_sys_rename fs/namei.c:4823 [inline]
 __x64_sys_rename+0x58/0x60 fs/namei.c:4823
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88812f1a0e40 of 4 bytes by task 20720 on cpu 0:
 __d_entry_type include/linux/dcache.h:395 [inline]
 d_is_symlink include/linux/dcache.h:425 [inline]
 step_into+0x171/0xee0 fs/namei.c:1804
 open_last_lookups fs/namei.c:3373 [inline]
 path_openat+0x102d/0x1ec0 fs/namei.c:3556
 do_filp_open+0x105/0x220 fs/namei.c:3586
 do_sys_openat2+0xb5/0x2b0 fs/open.c:1200
 do_sys_open fs/open.c:1216 [inline]
 __do_sys_open fs/open.c:1224 [inline]
 __se_sys_open fs/open.c:1220 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1220
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00400008 -> 0x00008108

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 20720 Comm: systemd-udevd Tainted: G        W         5.14.0-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	2021/09/09 13:09	upstream	a3fa7a101dcf	e2776ee4	.config	log	report			info	KCSAN: data-race in step_into / vfs_rename