KCSAN: data-race in __fsnotify_parent / vfs

KCSAN: data-race in __fsnotify_parent / vfs_unlink (2)
Status: auto-closed as invalid on 2020/11/19 20:53
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 389d, last: 369d

similar bugs (3):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __fsnotify_parent / vfs_unlink (3)	4	258d	316d	0/22	auto-closed as invalid on 2021/03/11 07:42
upstream	KCSAN: data-race in __fsnotify_parent / vfs_unlink (4)	6	140d	220d	0/22	auto-closed as invalid on 2021/07/07 08:07
upstream	KCSAN: data-race in __fsnotify_parent / vfs_unlink	2	589d	602d	0/22	auto-closed as invalid on 2020/05/19 08:17

Sample crash report:

==================================================================
BUG: KCSAN: data-race in __fsnotify_parent / vfs_unlink

write to 0xffff8881104d19c0 of 4 bytes by task 8704 on cpu 1:
 dont_mount include/linux/dcache.h:354 [inline]
 vfs_unlink+0x271/0x3c0 fs/namei.c:3834
 do_unlinkat+0x28a/0x4d0 fs/namei.c:3896
 __do_sys_unlink fs/namei.c:3942 [inline]
 __se_sys_unlink fs/namei.c:3940 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:3940
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881104d19c0 of 4 bytes by task 24015 on cpu 0:
 __fsnotify_parent+0x79/0x470 fs/notify/fsnotify.c:180
 fsnotify_parent include/linux/fsnotify.h:68 [inline]
 fsnotify_file include/linux/fsnotify.h:90 [inline]
 fsnotify_open include/linux/fsnotify.h:268 [inline]
 do_sys_openat2+0x492/0x500 fs/open.c:1173
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_creat fs/open.c:1258 [inline]
 __se_sys_creat fs/open.c:1252 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1252
 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: 0 PID: 24015 Comm: syz-executor.0 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 24015 Comm: syz-executor.0 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x10f/0x19d lib/dump_stack.c:118
 panic+0x207/0x64a kernel/panic.c:231
 kcsan_report+0x684/0x690 kernel/kcsan/report.c:634
 kcsan_setup_watchpoint+0x4b9/0x540 kernel/kcsan/core.c:568
 __fsnotify_parent+0x79/0x470 fs/notify/fsnotify.c:180
 fsnotify_parent include/linux/fsnotify.h:68 [inline]
 fsnotify_file include/linux/fsnotify.h:90 [inline]
 fsnotify_open include/linux/fsnotify.h:268 [inline]
 do_sys_openat2+0x492/0x500 fs/open.c:1173
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_creat fs/open.c:1258 [inline]
 __se_sys_creat fs/open.c:1252 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1252
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45de59
Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f3450673c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 0000000000002980 RCX: 000000000045de59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000080
RBP: 000000000118c000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bfd4
R13: 00007ffe540966bf R14: 00007f34506749c0 R15: 000000000118bfd4
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/10/15 20:39	upstream	726eb70e0d34	6e262c73	.config	log	report			info
ci2-upstream-kcsan-gce	2020/09/25 13:03	upstream	171d4ff79f96	4a006f63	.config	log	report			info