===============================
[ INFO: suspicious RCU usage. ]
4.4.174+ #4 Not tainted
-------------------------------
net/ipv6/ip6_fib.c:1465 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 1, debug_locks = 0
5 locks held by syz-executor.1/2151:
 #0:  (rcu_read_lock){......}, at: [<ffffffff819548bc>] INIT_LIST_HEAD include/linux/list.h:28 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff819548bc>] avc_compute_av+0xac/0x610 security/selinux/avc.c:973
 #1:  (((&net->ipv6.ip6_fib_timer))){+.-...}, at: [<ffffffff8125822e>] lockdep_copy_map include/linux/lockdep.h:165 [inline]
 #1:  (((&net->ipv6.ip6_fib_timer))){+.-...}, at: [<ffffffff8125822e>] call_timer_fn+0xde/0x850 kernel/time/timer.c:1175
 #2:  (fib6_gc_lock){+.-...}, at: [<ffffffff825fa33a>] spin_lock_bh include/linux/spinlock.h:307 [inline]
 #2:  (fib6_gc_lock){+.-...}, at: [<ffffffff825fa33a>] fib6_run_gc+0x3a/0x230 net/ipv6/ip6_fib.c:1811
 #3:  (rcu_read_lock){......}, at: [<ffffffff825f1ee0>] __fib6_clean_all+0x0/0x240 net/ipv6/ip6_fib.c:1698
 #4:  (&tb->tb6_lock){++--..}, at: [<ffffffff825f1fc8>] __fib6_clean_all+0xe8/0x240 net/ipv6/ip6_fib.c:1712

stack backtrace:
CPU: 0 PID: 2151 Comm: syz-executor.1 Not tainted 4.4.174+ #4
 0000000000000000 53c260b8d410e056 ffff8801db607940 ffffffff81aad1a1
 ffff88008eda2c40 0000000000000000[ 1727.742444] audit: type=1400 audit(1553073576.758:1920): avc:  denied  { create } for  pid=16047 comm="syz-executor.4" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
 0000000000000001 00000000000005b9
 ffff8801d68bc740 ffff8801db607970 ffffffff813ab7d6 ffff8801db607b90
Call Trace:
 <IRQ>  [<ffffffff81aad1a1>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ>  [<ffffffff81aad1a1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff813ab7d6>] lockdep_rcu_suspicious.cold+0x10a/0x149 kernel/locking/lockdep.c:4305
 [<ffffffff825f9ada>] fib6_del+0x7ea/0xae0 net/ipv6/ip6_fib.c:1465
 [<ffffffff825fa06c>] fib6_clean_node+0x29c/0x500 net/ipv6/ip6_fib.c:1652
 [<ffffffff825f1830>] fib6_walk_continue+0x3e0/0x630 net/ipv6/ip6_fib.c:1578
 [<ffffffff825f1d71>] fib6_walk+0x91/0xe0 net/ipv6/ip6_fib.c:1623
 [<ffffffff825f1ea8>] fib6_clean_tree+0xe8/0x120 net/ipv6/ip6_fib.c:1697
 [<ffffffff825f1fe0>] __fib6_clean_all+0x100/0x240 net/ipv6/ip6_fib.c:1713
 [<ffffffff825fa3af>] fib6_clean_all net/ipv6/ip6_fib.c:1724 [inline]
 [<ffffffff825fa3af>] fib6_run_gc+0xaf/0x230 net/ipv6/ip6_fib.c:1821
 [<ffffffff825fa54d>] fib6_gc_timer_cb+0x1d/0x30 net/ipv6/ip6_fib.c:1836
 [<ffffffff812582dd>] call_timer_fn+0x18d/0x850 kernel/time/timer.c:1185
 [<ffffffff81258ebf>] __run_timers kernel/time/timer.c:1261 [inline]
 [<ffffffff81258ebf>] run_timer_softirq+0x51f/0xb70 kernel/time/timer.c:1444
 [<ffffffff8271bb16>] __do_softirq+0x226/0xa3f kernel/softirq.c:273
 [<ffffffff810e1a8a>] invoke_softirq kernel/softirq.c:350 [inline]
 [<ffffffff810e1a8a>] irq_exit+0x10a/0x150 kernel/softirq.c:391
 [<ffffffff8271b24e>] exiting_irq arch/x86/include/asm/apic.h:652 [inline]
 [<ffffffff8271b24e>] smp_apic_timer_interrupt+0x7e/0xb0 arch/x86/kernel/apic/apic.c:926
 [<ffffffff8271a59d>] apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:768
 <EOI>  [<ffffffff8271802f>] ? arch_local_irq_restore arch/x86/include/asm/paravirt.h:812 [inline]
 <EOI>  [<ffffffff8271802f>] ? __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:162 [inline]
 <EOI>  [<ffffffff8271802f>] ? _raw_spin_unlock_irqrestore+0x5f/0x70 kernel/locking/spinlock.c:191
 [<ffffffff8195365c>] spin_unlock_irqrestore include/linux/spinlock.h:362 [inline]
 [<ffffffff8195365c>] avc_reclaim_node security/selinux/avc.c:541 [inline]
 [<ffffffff8195365c>] avc_alloc_node security/selinux/avc.c:559 [inline]
 [<ffffffff8195365c>] avc_alloc_node+0x31c/0x3c0 security/selinux/avc.c:547
 [<ffffffff81954992>] avc_insert security/selinux/avc.c:670 [inline]
 [<ffffffff81954992>] avc_compute_av+0x182/0x610 security/selinux/avc.c:976
 [<ffffffff819566e5>] avc_has_perm_noaudit security/selinux/avc.c:1112 [inline]
 [<ffffffff819566e5>] avc_has_perm+0x355/0x3a0 security/selinux/avc.c:1146
 [<ffffffff8195fd1d>] sock_has_perm+0x29d/0x400 security/selinux/hooks.c:4066
 [<ffffffff8195ff5f>] selinux_socket_getsockopt+0x3f/0x50 security/selinux/hooks.c:4346
 [<ffffffff81951643>] security_socket_getsockopt+0x83/0xc0 security/security.c:1259
 [<ffffffff821dcd0a>] SYSC_getsockopt net/socket.c:1801 [inline]
 [<ffffffff821dcd0a>] SyS_getsockopt+0xca/0x220 net/socket.c:1793
 [<ffffffff82718ba1>] entry_SYSCALL_64_fastpath+0x1e/0x9a
audit: type=1400 audit(1553073578.288:1921): avc:  denied  { create } for  pid=16147 comm="syz-executor.0" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
audit: type=1400 audit(1553073579.028:1922): avc:  denied  { create } for  pid=16147 comm="syz-executor.0" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0