netlink: 24 bytes leftover after parsing attributes in process `syz-executor1'.

===============================
[ INFO: suspicious RCU usage. ]
4.9.101-gaef17a5 #32 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
3 locks held by syz-executor3/3772:
 #0:  (tasklist_lock){.+.+..}, at: [<ffffffff81144472>] do_wait+0x392/0x950 kernel/exit.c:1562
 #1:  (rcu_read_lock){......}, at: [<ffffffff81cf5f04>] avc_has_perm_noaudit security/selinux/avc.c:1108 [inline]
 #1:  (rcu_read_lock){......}, at: [<ffffffff81cf5f04>] avc_has_perm+0xb4/0x4f0 security/selinux/avc.c:1148
 #2:  (rcu_callback){......}, at: [<ffffffff812858ae>] __rcu_reclaim kernel/rcu/rcu.h:108 [inline]
 #2:  (rcu_callback){......}, at: [<ffffffff812858ae>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 #2:  (rcu_callback){......}, at: [<ffffffff812858ae>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 #2:  (rcu_callback){......}, at: [<ffffffff812858ae>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 #2:  (rcu_callback){......}, at: [<ffffffff812858ae>] rcu_process_callbacks+0x98e/0x12b0 kernel/rcu/tree.c:3037

stack backtrace:
CPU: 0 PID: 3772 Comm: syz-executor3 Not tainted 4.9.101-gaef17a5 #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db207d60 ffffffff81eb1009 ffff8801cbcee000 0000000000000000
 0000000000000002 ffffffff83c6da00 ffff8801da2fe3d8 ffff8801db207d90
 ffffffff81423f99 ffff8801da2fe280 ffff8801d839ee48 ffff8801d839e648
Call Trace:
 <IRQ> [  258.751488]  [<ffffffff81eb1009>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [  258.751488]  [<ffffffff81eb1009>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81423f99>] lockdep_rcu_suspicious.cold.48+0x110/0x141 kernel/locking/lockdep.c:4455
 [<ffffffff81282148>] synchronize_rcu+0x68/0x90 kernel/rcu/tree_plugin.h:669
 [<ffffffff836b7cfa>] __l2tp_session_unhash+0x38a/0x520 net/l2tp/l2tp_core.c:1796
 [<ffffffff836b8087>] l2tp_tunnel_closeall+0x1f7/0x350 net/l2tp/l2tp_core.c:1364
 [<ffffffff836b8942>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1324
 [<ffffffff8301d095>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff812857ce>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff812857ce>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff812857ce>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff812857ce>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff812857ce>] rcu_process_callbacks+0x8ae/0x12b0 kernel/rcu/tree.c:3037
 [<ffffffff839fb47b>] __do_softirq+0x20b/0x937 kernel/softirq.c:284
 [<ffffffff81149077>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff81149077>] irq_exit+0x147/0x190 kernel/softirq.c:405
 [<ffffffff839fa061>] exiting_irq arch/x86/include/asm/apic.h:659 [inline]
 [<ffffffff839fa061>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:960
 [<ffffffff839f61f0>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> [  258.865068]  [<ffffffff81cf60a7>] ? avc_has_perm_noaudit security/selinux/avc.c:1118 [inline]
 <EOI> [  258.865068]  [<ffffffff81cf60a7>] ? avc_has_perm+0x257/0x4f0 security/selinux/avc.c:1148
 [<ffffffff81d083ac>] task_has_perm+0x1fc/0x330 security/selinux/hooks.c:1615
 [<ffffffff81d08503>] selinux_task_wait+0x23/0x30 security/selinux/hooks.c:3954
 [<ffffffff81cef243>] security_task_wait+0x73/0xb0 security/security.c:1032
 [<ffffffff81140d51>] wait_consider_task+0x2a1/0x3630 kernel/exit.c:1381
 [<ffffffff81144503>] do_wait_thread kernel/exit.c:1494 [inline]
 [<ffffffff81144503>] do_wait+0x423/0x950 kernel/exit.c:1565
 [<ffffffff8114543b>] SYSC_wait4 kernel/exit.c:1697 [inline]
 [<ffffffff8114543b>] SyS_wait4+0x12b/0x1f0 kernel/exit.c:1662
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f4893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
ODEBUG: object ffff8801db207ce8 is NOT on stack ffff8801a6e18000, but annotated
------------[ cut here ]------------
WARNING: CPU: 0 PID: 3772 at lib/debugobjects.c:303 debug_object_is_on_stack lib/debugobjects.c:303 [inline]
WARNING: CPU: 0 PID: 3772 at lib/debugobjects.c:303 __debug_object_init.cold.10+0x6b/0x2b0 lib/debugobjects.c:329