KCSAN: data-race in dput / vfs

KCSAN: data-race in dput / vfs_rename (2)
Status: auto-closed as invalid on 2020/05/27 13:23
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 551d, last: 551d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in dput / vfs_rename (4)	1	346d	346d	0/22	auto-closed as invalid on 2020/11/13 11:07
upstream	KCSAN: data-race in dput / vfs_rename (3)	2	437d	458d	0/22	auto-closed as invalid on 2020/08/14 12:58
upstream	KCSAN: data-race in dput / vfs_rename (5)	5	194d	253d	0/22	auto-closed as invalid on 2021/04/14 19:39
upstream	KCSAN: data-race in dput / vfs_rename	1	660d	660d	0/22	auto-closed as invalid on 2020/02/09 03:47

Sample crash report:

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

write to 0xffff888129a09780 of 4 bytes by task 7917 on cpu 1:
 dont_mount include/linux/dcache.h:352 [inline]
 vfs_rename+0x90a/0x10b0 fs/namei.c:4561
 do_renameat2+0x9e8/0xa50 fs/namei.c:4701
 __do_sys_rename fs/namei.c:4747 [inline]
 __se_sys_rename fs/namei.c:4745 [inline]
 __x64_sys_rename+0x44/0x60 fs/namei.c:4745
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888129a09780 of 4 bytes by task 4028 on cpu 0:
 fast_dput fs/dcache.c:727 [inline]
 dput+0x4b/0x700 fs/dcache.c:846
 __fput+0x28c/0x4f0 fs/file_table.c:293
 ____fput+0x1b/0x30 fs/file_table.c:313
 task_work_run+0xf5/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2ae/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4028 Comm: udevd Not tainted 5.6.0-rc1-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	2020/03/18 13:19	https://github.com/google/ktsan.git kcsan	941e0d917bbf	0a96a13c	.config	log	report