KCSAN: data-race in step_into / vfs

KCSAN: data-race in step_into / vfs_rename
Status: closed as invalid on 2020/06/18 14:24
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 512d, last: 462d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in step_into / vfs_rename (5)	1	55d	55d	0/22	auto-closed as invalid on 2021/08/31 22:21
upstream	KCSAN: data-race in step_into / vfs_rename (2)	1	454d	454d	0/22	auto-closed as invalid on 2020/07/29 00:43
upstream	KCSAN: data-race in step_into / vfs_rename (3)	3	336d	368d	0/22	auto-closed as invalid on 2020/11/24 01:44
upstream	KCSAN: data-race in step_into / vfs_rename (4)	1	264d	264d	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 0xffff8880b55a3f00 of 4 bytes by task 11748 on cpu 1:
 dont_mount include/linux/dcache.h:352 [inline]
 vfs_rename+0x985/0x1130 fs/namei.c:4297
 do_renameat2+0x9e8/0xa50 fs/namei.c:4437
 __do_sys_rename fs/namei.c:4483 [inline]
 __se_sys_rename fs/namei.c:4481 [inline]
 __x64_sys_rename+0x44/0x60 fs/namei.c:4481
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880b55a3f00 of 4 bytes by task 5282 on cpu 0:
 __follow_mount_rcu fs/namei.c:1302 [inline]
 handle_mounts fs/namei.c:1359 [inline]
 step_into+0xb2/0x1090 fs/namei.c:1676
 open_last_lookups fs/namei.c:3178 [inline]
 path_openat+0x34e/0x23d0 fs/namei.c:3343
 do_filp_open+0x11e/0x1b0 fs/namei.c:3373
 do_sys_openat2+0x52e/0x680 fs/open.c:1148
 do_sys_open+0xa2/0x110 fs/open.c:1164
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_open fs/open.c:1170 [inline]
 __se_sys_open fs/open.c:1168 [inline]
 __x64_sys_open+0x50/0x60 fs/open.c:1168
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5282 Comm: systemd-udevd Not tainted 5.7.0-rc1-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	2020/06/15 18:47	https://github.com/google/ktsan.git kcsan	7c3cd68e5d38	8e3ab941	.config	log	report
ci2-upstream-kcsan-gce	2020/04/27 05:22	https://github.com/google/ktsan.git kcsan	7c3cd68e5d38	0ce7569e	.config	log	report