WARNING: suspicious RCU usage in pid

WARNING: suspicious RCU usage in pid_task
Status: upstream: reported C repro on 2018/06/16 06:47
Reported-by: syzbot+c2d4c3ae3fd90bbaf059@syzkaller.appspotmail.com
First crash: 1326d, last: 1222d

Cause bisection: introduced by (bisect log) :
commit 23fb93a4d3f118a900790066d03368a296dce0d6
Author: David Ahern <dsahern@gmail.com>
Date: Wed Apr 18 00:33:23 2018 +0000

net/ipv6: Cleanup exception and cache route handling

Crash: unregister_netdevice: waiting for DEV to become free (log)
Repro: C syz .config

Fix bisection: fixed by (bisect log) [no-op commit]:
commit 761f60261b4401aa368d71d431b4c218af0efcee
Author: Xin Long <lucien.xin@gmail.com>
Date: Tue Nov 13 16:48:28 2018 +0000

ipv6: fix a dst leak when removing its exception

Sample crash report:

bpfilter: read fail -512

=============================
WARNING: suspicious RCU usage
4.18.0-rc2+ #117 Not tainted
-----------------------------
kernel/pid.c:323 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz-executor106/7744:
 #0: 00000000bee82115 (bpfilter_lock){+.+.}, at: __bpfilter_process_sockopt+0x1c5/0x39b net/bpfilter/bpfilter_kern.c:67

stack backtrace:
CPU: 1 PID: 7744 Comm: syz-executor106 Not tainted 4.18.0-rc2+ #117
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+0x1c9/0x2b4 lib/dump_stack.c:113
 lockdep_rcu_suspicious+0x14a/0x153 kernel/locking/lockdep.c:4562
 pid_task+0x1ce/0x200 kernel/pid.c:322
 shutdown_umh.constprop.0+0x33/0x7c net/bpfilter/bpfilter_kern.c:29
 __stop_umh net/bpfilter/bpfilter_kern.c:41 [inline]
 __bpfilter_process_sockopt.cold.1+0x9b/0xa0 net/bpfilter/bpfilter_kern.c:81
 bpfilter_mbox_request+0x4d/0xb0 net/ipv4/bpfilter/sockopt.c:25
 bpfilter_ip_set_sockopt+0x33/0x40 net/ipv4/bpfilter/sockopt.c:31
 ip_setsockopt+0x124/0x140 net/ipv4/ip_sockglue.c:1250
 dccp_setsockopt+0x96/0xf0 net/dccp/proto.c:565
 sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3040
 __sys_setsockopt+0x1c5/0x3b0 net/socket.c:1947
 __do_sys_setsockopt net/socket.c:1958 [inline]
 __se_sys_setsockopt net/socket.c:1955 [inline]
 __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1955
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x44cdb9
Code: e8 6c bd 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 cb d2 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007f63b04a8d18 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000006dfce4 RCX: 000000000044cdb9
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000027
RBP: 00000000006dfce0 R08: 0000000000000000 R09: 65732f636f72702f
R10: 0000000020000000 R11: 0000000000000246 R12: 00007f63b04a8d20
R13: 0100000000000000 R14: 6273752f7665642f R15: 0000000000000034

Crashes (72):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro
ci-upstream-kasan-gce-root	2018/06/25 17:44	upstream	6f0d349d922b	2064fc5c	.config	log	report	syz	C
ci-upstream-kasan-gce-selinux-root	2018/09/24 15:13	upstream	02214bfc89c7	2f485cdf	.config	log	report
ci-upstream-kasan-gce-selinux-root	2018/09/23 23:40	upstream	6bf4ca7fbc85	28d9ac76	.config	log	report
ci-upstream-kasan-gce-selinux-root	2018/09/23 21:23	upstream	6bf4ca7fbc85	28d9ac76	.config	log	report
ci-upstream-kasan-gce-selinux-root	2018/09/22 09:37	upstream	10dc890d4228	37079712	.config	log	report
ci-upstream-kasan-gce-selinux-root	2018/09/22 01:26	upstream	10dc890d4228	37079712	.config	log	report
ci-upstream-kasan-gce-selinux-root	2018/09/22 00:10	upstream	10dc890d4228	37079712	.config	log	report
ci-upstream-kasan-gce-selinux-root	2018/09/21 09:14	upstream	234b69e3e089	37079712	.config	log	report
ci-upstream-kasan-gce-selinux-root	2018/09/20 19:09	upstream	ae596de1a0c8	6cee973c	.config	log	report
ci-upstream-kasan-gce-selinux-root	2018/09/10 15:50	upstream	11da3a7f84f1	f167cb6b	.config	log	report
ci-upstream-kasan-gce-selinux-root	2018/09/10 07:41	upstream	11da3a7f84f1	6b5120a4	.config	log	report
ci-upstream-kasan-gce	2018/09/10 04:47	upstream	9a5682765a2e	6b5120a4	.config	log	report
ci-upstream-kasan-gce	2018/09/10 02:04	upstream	9a5682765a2e	6b5120a4	.config	log	report
ci-upstream-kasan-gce	2018/09/09 20:46	upstream	9a5682765a2e	6b5120a4	.config	log	report
ci-upstream-kasan-gce-smack-root	2018/09/09 10:31	upstream	f8f65382c98a	6b5120a4	.config	log	report
ci-upstream-kasan-gce-smack-root	2018/09/08 15:11	upstream	3d0e7a9e00fd	6b5120a4	.config	log	report
ci-upstream-kasan-gce	2018/09/07 23:49	upstream	a49a9dcce802	69cfeb80	.config	log	report
ci-upstream-kasan-gce	2018/09/07 21:20	upstream	a49a9dcce802	69cfeb80	.config	log	report
ci-upstream-kasan-gce-root	2018/09/07 19:18	upstream	a49a9dcce802	69cfeb80	.config	log	report
ci-upstream-kasan-gce-root	2018/09/07 02:39	upstream	ca16eb342ebe	e30d3b52	.config	log	report
ci-upstream-kasan-gce-smack-root	2018/09/07 00:31	upstream	ca16eb342ebe	e30d3b52	.config	log	report
ci-upstream-kasan-gce-root	2018/09/06 14:30	upstream	b36fdc6853a3	0bb7a7eb	.config	log	report
ci-upstream-kasan-gce-smack-root	2018/09/06 11:00	upstream	b36fdc6853a3	0bb7a7eb	.config	log	report
ci-upstream-kasan-gce	2018/09/06 04:40	upstream	b36fdc6853a3	873745f2	.config	log	report
ci-upstream-kasan-gce-selinux-root	2018/09/06 03:00	upstream	b36fdc6853a3	873745f2	.config	log	report
ci-upstream-kasan-gce	2018/09/05 18:45	upstream	0e9b10395018	196410e4	.config	log	report
ci-upstream-kasan-gce	2018/09/05 13:40	upstream	28619527b8a7	196410e4	.config	log	report
ci-upstream-kasan-gce-root	2018/09/04 22:56	upstream	28619527b8a7	a4718693	.config	log	report
ci-upstream-kasan-gce-root	2018/09/03 18:25	upstream	60c1f89241d4	a4718693	.config	log	report
ci-upstream-kasan-gce	2018/09/03 14:18	upstream	60c1f89241d4	a4718693	.config	log	report
ci-upstream-kasan-gce	2018/09/03 12:25	upstream	60c1f89241d4	a4718693	.config	log	report
ci-upstream-kasan-gce-root	2018/09/03 04:32	upstream	899ba79553cf	a4718693	.config	log	report
ci-upstream-net-this-kasan-gce	2018/09/23 08:59	net	8ac1ee6f4d62	37079712	.config	log	report
ci-upstream-net-kasan-gce	2018/09/16 03:15	net-next	ee4fccbee7d3	a343a400	.config	log	report
ci-upstream-net-kasan-gce	2018/09/10 21:40	net-next	11957be20ff6	f167cb6b	.config	log	report
ci-upstream-net-kasan-gce	2018/09/08 04:11	net-next	98cdb4807123	6b5120a4	.config	log	report
ci-upstream-net-kasan-gce	2018/06/12 01:38	net-next	f0dc7f9c6dd9	112eec79	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2018/09/07 01:33	linux-next	f2b6e66e9885	e30d3b52	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2018/09/05 21:25	linux-next	f2b6e66e9885	196410e4	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2018/09/04 19:37	linux-next	f2b6e66e9885	a4718693	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2018/09/03 19:11	linux-next	dceb9092b16b	a4718693	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2018/09/03 18:19	linux-next	dceb9092b16b	a4718693	.config	log	report
ci-upstream-linux-next-kasan-gce-root	2018/09/03 07:02	linux-next	dceb9092b16b	a4718693	.config	log	report