KCSAN: data-race in fasync_remove_entry / kill

KCSAN: data-race in fasync_remove_entry / kill_fasync (4)
Status: auto-closed as invalid on 2021/06/23 11:06
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 125d, last: 125d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in fasync_remove_entry / kill_fasync (2)	1	394d	394d	0/22	auto-closed as invalid on 2020/09/27 12:17
upstream	KCSAN: data-race in fasync_remove_entry / kill_fasync (5)	2	56d	58d	0/22	auto-closed as invalid on 2021/08/31 22:21
upstream	KCSAN: data-race in fasync_remove_entry / kill_fasync (3)	1	277d	277d	0/22	auto-closed as invalid on 2021/01/22 14:57
upstream	KCSAN: data-race in fasync_remove_entry / kill_fasync	82	448d	606d	0/22	auto-closed as invalid on 2020/08/04 12:11

Sample crash report:

==================================================================
BUG: KCSAN: data-race in fasync_remove_entry / kill_fasync

write to 0xffff88810699fa58 of 8 bytes by task 5698 on cpu 0:
 fasync_remove_entry+0xd9/0x180 fs/fcntl.c:894
 fasync_helper+0x92/0xc0 fs/fcntl.c:993
 sock_fasync+0x5c/0xc0 net/socket.c:1283
 __fput+0x49f/0x4e0 fs/file_table.c:277
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0xae/0x130 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810699fa58 of 8 bytes by task 5695 on cpu 1:
 kill_fasync+0x1e/0x160 fs/fcntl.c:1031
 sock_wake_async+0xea/0x100 net/socket.c:1312
 sk_wake_async include/net/sock.h:2311 [inline]
 unix_release_sock+0x383/0x6e0 net/unix/af_unix.c:553
 unix_release+0x2f/0x50 net/unix/af_unix.c:859
 __sock_release net/socket.c:599 [inline]
 sock_close+0x6c/0x150 net/socket.c:1258
 __fput+0x25b/0x4e0 fs/file_table.c:280
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0xae/0x130 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5695 Comm: syz-executor.4 Not tainted 5.13.0-rc2-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	2021/05/19 11:03	upstream	8ac91e6c6033	a343ba6b	.config	log	report			info	KCSAN: data-race in fasync_remove_entry / kill_fasync