audit: type=1400 audit(1516820876.601:6239): avc:  denied  { dac_read_search } for  pid=25337 comm="syz-executor2" capability=2  scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1

===============================
[ INFO: suspicious RCU usage. ]
4.9.78-ge9dabe6 #19 Not tainted
-------------------------------
kernel/rcu/tree_plugin.h:672 Illegal synchronize_rcu() in RCU read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
2 locks held by syz-executor0/25350:
 #0:  (rcu_read_lock){......}, at: [<ffffffff81bd91bd>] INIT_LIST_HEAD include/linux/list.h:28 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81bd91bd>] avc_compute_av+0xad/0x640 security/selinux/avc.c:975
 #1:  (rcu_callback){......}, at: [<ffffffff81293257>] __rcu_reclaim kernel/rcu/rcu.h:108 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81293257>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81293257>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81293257>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff81293257>] rcu_process_callbacks+0x977/0x1300 kernel/rcu/tree.c:3037

stack backtrace:
CPU: 0 PID: 25350 Comm: syz-executor0 Not tainted 4.9.78-ge9dabe6 #19
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db207d50 ffffffff81d943a9 ffff8801c1b79800 0000000000000000
 0000000000000002 ffffffff83a6d440 ffff8801c6a9a658 ffff8801db207d80
 ffffffff81238329 ffff8801c6a9a500 ffff8801cb510848 ffff8801cb510048
Call Trace:
 <IRQ> 
 [<ffffffff81d943a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d943a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81238329>] lockdep_rcu_suspicious+0x139/0x180 kernel/locking/lockdep.c:4455
 [<ffffffff8128fb28>] synchronize_rcu+0x68/0x90 kernel/rcu/tree_plugin.h:669
 [<ffffffff83583d25>] __l2tp_session_unhash+0x3d5/0x550 net/l2tp/l2tp_core.c:1792
 [<ffffffff83584087>] l2tp_tunnel_closeall+0x1e7/0x3a0 net/l2tp/l2tp_core.c:1364
 [<ffffffff835849ae>] l2tp_tunnel_destruct+0x30e/0x5a0 net/l2tp/l2tp_core.c:1324
 [<ffffffff82ee5033>] __sk_destruct+0x53/0x570 net/core/sock.c:1428
 [<ffffffff81293178>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff81293178>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff81293178>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff81293178>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff81293178>] rcu_process_callbacks+0x898/0x1300 kernel/rcu/tree.c:3037
 [<ffffffff838b98c6>] __do_softirq+0x206/0x951 kernel/softirq.c:284
 [<ffffffff81146be5>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff81146be5>] irq_exit+0x165/0x190 kernel/softirq.c:405
 [<ffffffff838b84db>] exiting_irq arch/x86/include/asm/apic.h:659 [inline]
 [<ffffffff838b84db>] smp_apic_timer_interrupt+0x7b/0xa0 arch/x86/kernel/apic/apic.c:960
 [<ffffffff838b4760>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:752
 <EOI> 
 [<ffffffff81bd840a>] spin_unlock_irqrestore include/linux/spinlock.h:362 [inline]
 [<ffffffff81bd840a>] avc_reclaim_node security/selinux/avc.c:543 [inline]
 [<ffffffff81bd840a>] avc_alloc_node+0x27a/0x3e0 security/selinux/avc.c:561
 [<ffffffff81bd9292>] avc_insert security/selinux/avc.c:672 [inline]
 [<ffffffff81bd9292>] avc_compute_av+0x182/0x640 security/selinux/avc.c:978
 [<ffffffff81bda161>] avc_has_extended_perms+0x481/0xf10 security/selinux/avc.c:1026
 [<ffffffff81bea621>] ioctl_has_perm security/selinux/hooks.c:3447 [inline]
 [<ffffffff81bea621>] selinux_file_ioctl+0x331/0x530 security/selinux/hooks.c:3495
 [<ffffffff81bd2e0d>] security_file_ioctl+0x7d/0xb0 security/security.c:797
 [<ffffffff815aef8a>] SYSC_ioctl fs/ioctl.c:692 [inline]
 [<ffffffff815aef8a>] SyS_ioctl+0x4a/0xc0 fs/ioctl.c:685
 [<ffffffff838b2c6e>] entry_SYSCALL_64_fastpath+0x29/0xe8
ODEBUG: object is not on stack, but annotated
------------[ cut here ]------------
WARNING: CPU: 0 PID: 25350 at lib/debugobjects.c:300 debug_object_is_on_stack lib/debugobjects.c:300 [inline]
WARNING: CPU: 0 PID: 25350 at lib/debugobjects.c:300 __debug_object_init+0x526/0xc40 lib/debugobjects.c:326