KCSAN: data-race in fasync_remove_entry / kill

KCSAN: data-race in fasync_remove_entry / kill_fasync (5)
Status: auto-closed as invalid on 2021/08/31 22:21
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 86d, last: 84d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in fasync_remove_entry / kill_fasync (2)	1	422d	422d	0/22	auto-closed as invalid on 2020/09/27 12:17
upstream	KCSAN: data-race in fasync_remove_entry / kill_fasync (4)	1	153d	153d	0/22	auto-closed as invalid on 2021/06/23 11:06
upstream	KCSAN: data-race in fasync_remove_entry / kill_fasync (3)	1	305d	305d	0/22	auto-closed as invalid on 2021/01/22 14:57
upstream	KCSAN: data-race in fasync_remove_entry / kill_fasync	82	476d	634d	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 0xffff8881068d5658 of 8 bytes by task 22262 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:1325
 __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:175 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x49/0x90 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881068d5658 of 8 bytes by task 22266 on cpu 1:
 kill_fasync+0x1e/0x160 fs/fcntl.c:1031
 sock_wake_async+0xea/0x100 net/socket.c:1354
 sk_wake_async include/net/sock.h:2327 [inline]
 unix_release_sock+0x3aa/0x6f0 net/unix/af_unix.c:562
 unix_release+0x2f/0x50 net/unix/af_unix.c:867
 __sock_release net/socket.c:648 [inline]
 sock_close+0x6c/0x150 net/socket.c:1300
 __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
 get_signal+0x156c/0x15e0 kernel/signal.c:2581
 arch_do_signal_or_restart+0x2a/0x220 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x109/0x190 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x49/0x90 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff888101d01690 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22266 Comm: syz-executor.1 Not tainted 5.14.0-rc3-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	2021/07/27 22:13	upstream	7d549995d4e0	17d6ab15	.config	log	report			info	KCSAN: data-race in fasync_remove_entry / kill_fasync
ci2-upstream-kcsan-gce	2021/07/25 21:26	upstream	d8079fac1681	4d1b57d4	.config	log	report			info	KCSAN: data-race in fasync_remove_entry / kill_fasync