KCSAN: data-race in d_delete / step

KCSAN: data-race in d_delete / step_into (5)
Status: auto-closed as invalid on 2021/08/17 20:13
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 133d, last: 98d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in d_delete / step_into	2	518d	519d	0/22	closed as invalid on 2020/06/18 14:13
upstream	KCSAN: data-race in d_delete / step_into (3)	1	275d	275d	0/22	auto-closed as invalid on 2021/02/21 16:24
upstream	KCSAN: data-race in d_delete / step_into (2)	2	450d	466d	0/22	auto-closed as invalid on 2020/08/30 20:17
upstream	KCSAN: data-race in d_delete / step_into (4)	3	210d	223d	0/22	auto-closed as invalid on 2021/05/17 11:48

Sample crash report:

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

write to 0xffff888106de0840 of 4 bytes by task 10847 on cpu 1:
 d_delete+0x6e/0xe0 fs/dcache.c:2504
 vfs_unlink+0x3d8/0x400 fs/namei.c:4049
 do_unlinkat+0x238/0x4f0 fs/namei.c:4102
 __do_sys_unlink fs/namei.c:4149 [inline]
 __se_sys_unlink fs/namei.c:4147 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:4147
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888106de0840 of 4 bytes by task 1038 on cpu 0:
 __d_entry_type include/linux/dcache.h:395 [inline]
 d_is_symlink include/linux/dcache.h:425 [inline]
 step_into+0x16c/0xee0 fs/namei.c:1793
 walk_component+0x190/0x350 fs/namei.c:1965
 lookup_last fs/namei.c:2414 [inline]
 path_lookupat+0x12d/0x3d0 fs/namei.c:2438
 filename_lookup+0x118/0x3b0 fs/namei.c:2467
 user_path_at_empty+0x3b/0x50 fs/namei.c:2747
 do_readlinkat+0x87/0x200 fs/stat.c:425
 __do_sys_readlink fs/stat.c:458 [inline]
 __se_sys_readlink fs/stat.c:455 [inline]
 __x64_sys_readlink+0x43/0x50 fs/stat.c:455
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00600108 -> 0x00008008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1038 Comm: systemd-udevd Tainted: G        W         5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (3):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/07/13 20:08	upstream	40226a3d96ef	70168d5c	.config	log	report	info	KCSAN: data-race in d_delete / step_into
ci2-upstream-kcsan-gce	2021/07/07 18:54	upstream	3dbdb38e2869	95793bce	.config	log	report	info	KCSAN: data-race in d_delete / step_into
ci2-upstream-kcsan-gce	2021/06/08 17:28	upstream	4c8684fe555e	5c2fe346	.config	log	report	info	KCSAN: data-race in d_delete / step_into