===============================
[ INFO: suspicious RCU usage. ]
4.9.141+ #1 Not tainted
-------------------------------
net/ipv6/ip6_fib.c:1471 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
7 locks held by sshd/2069:
 #0:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff824e252d>] lock_sock include/net/sock.h:1404 [inline]
 #0:  (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff824e252d>] tcp_sendmsg+0xbd/0x2fd0 net/ipv4/tcp.c:1140
 #1:  (rcu_read_lock){......}, at: [<ffffffff824b4dbe>] read_pnet include/net/net_namespace.h:271 [inline]
 #1:  (rcu_read_lock){......}, at: [<ffffffff824b4dbe>] sock_net include/net/sock.h:2207 [inline]
 #1:  (rcu_read_lock){......}, at: [<ffffffff824b4dbe>] ip_queue_xmit+0x3e/0x18c0 net/ipv4/ip_output.c:425
 #2:  (rcu_read_lock){......}, at: [<ffffffff824b3daa>] __ip_local_out+0x1da/0x5b0 net/ipv4/ip_output.c:113
 #3:  (((&net->ipv6.ip6_fib_timer))){+.-...}, at: [<ffffffff812629ba>] lockdep_copy_map include/linux/lockdep.h:165 [inline]
 #3:  (((&net->ipv6.ip6_fib_timer))){+.-...}, at: [<ffffffff812629ba>] call_timer_fn+0xda/0x6e0 kernel/time/timer.c:1309
 #4:  (&(&net->ipv6.fib6_gc_lock)->rlock){+.-...}, at: [<ffffffff826ef615>] spin_lock_bh include/linux/spinlock.h:307 [inline]
 #4:  (&(&net->ipv6.fib6_gc_lock)->rlock){+.-...}, at: [<ffffffff826ef615>] fib6_run_gc+0xa5/0x2c0 net/ipv6/ip6_fib.c:1816
 #5:  (rcu_read_lock){......}, at: [<ffffffff826e6c70>] __fib6_clean_all+0x0/0x220 net/ipv6/ip6_fib.c:1703
 #6:  (&tb->tb6_lock){++--..}, at: [<ffffffff826e6d50>] __fib6_clean_all+0xe0/0x220 net/ipv6/ip6_fib.c:1717

stack backtrace:
CPU: 0 PID: 2069 Comm: sshd Not tainted 4.9.141+ #1
 ffff8801db6078c8 ffffffff81b42e79 ffff8801cf094740 0000000000000000
 0000000000000002 ffffffff82cc2480 ffffed003b6c0f67 ffff8801db6078f8
 ffffffff813fe948 ffff8801d74a6fc0 ffff8801db607ae8 ffff8801d74a6fc0
Call Trace:
 <IRQ> [  674.502497]  [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [  674.502497]  [<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff813fe948>] lockdep_rcu_suspicious.cold.32+0x110/0x141 kernel/locking/lockdep.c:4455
 [<ffffffff826eed80>] fib6_del+0x810/0xb10 net/ipv6/ip6_fib.c:1470
 [<ffffffff826ef2a0>] fib6_clean_node+0x220/0x4c0 net/ipv6/ip6_fib.c:1657
 [<ffffffff826e6545>] fib6_walk_continue+0x3e5/0x640 net/ipv6/ip6_fib.c:1583
 [<ffffffff826e6b01>] fib6_walk+0x91/0xf0 net/ipv6/ip6_fib.c:1628
 [<ffffffff826e6c33>] fib6_clean_tree+0xd3/0x110 net/ipv6/ip6_fib.c:1702
 [<ffffffff826e6d69>] __fib6_clean_all+0xf9/0x220 net/ipv6/ip6_fib.c:1718
 [<ffffffff826ef687>] fib6_clean_all net/ipv6/ip6_fib.c:1729 [inline]
 [<ffffffff826ef687>] fib6_run_gc+0x117/0x2c0 net/ipv6/ip6_fib.c:1826
 [<ffffffff826ef84c>] fib6_gc_timer_cb+0x1c/0x20 net/ipv6/ip6_fib.c:1841
 [<ffffffff81262a43>] call_timer_fn+0x163/0x6e0 kernel/time/timer.c:1319
 [<ffffffff812631f4>] expire_timers+0x234/0x580 kernel/time/timer.c:1359
 [<ffffffff81263748>] __run_timers kernel/time/timer.c:1674 [inline]
 [<ffffffff81263748>] run_timer_softirq+0x208/0x5e0 kernel/time/timer.c:1687
 [<ffffffff8281cb9e>] __do_softirq+0x20e/0x964 kernel/softirq.c:288
 [<ffffffff810efdbc>] invoke_softirq kernel/softirq.c:368 [inline]
 [<ffffffff810efdbc>] irq_exit+0x11c/0x150 kernel/softirq.c:409
 [<ffffffff8281b771>] exiting_irq arch/x86/include/asm/apic.h:669 [inline]
 [<ffffffff8281b771>] smp_apic_timer_interrupt+0x81/0xb0 arch/x86/kernel/apic/apic.c:962
 [<ffffffff8281902d>] apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> [  674.760538]  [<ffffffff82602b44>] ? nf_nat_ipv4_local_fn+0x244/0x470 net/ipv4/netfilter/nf_nat_l3proto_ipv4.c:414
 [<ffffffff82614eec>] iptable_nat_ipv4_local_fn+0x2c/0x40 net/ipv4/netfilter/iptable_nat.c:67
 [<ffffffff823ddae6>] nf_iterate+0x126/0x310 net/netfilter/core.c:324
 [<ffffffff823ddde4>] nf_hook_slow+0x114/0x1e0 net/netfilter/core.c:355
 [<ffffffff824b3ffe>] nf_hook_thresh include/linux/netfilter.h:191 [inline]
 [<ffffffff824b3ffe>] nf_hook include/linux/netfilter.h:203 [inline]
 [<ffffffff824b3ffe>] __ip_local_out+0x42e/0x5b0 net/ipv4/ip_output.c:113
 [<ffffffff824b41a9>] ip_local_out+0x29/0x180 net/ipv4/ip_output.c:122
 [<ffffffff824b5617>] ip_queue_xmit+0x897/0x18c0 net/ipv4/ip_output.c:500
 [<ffffffff82519ebb>] __tcp_transmit_skb+0x18bb/0x2df0 net/ipv4/tcp_output.c:1041
 [<ffffffff8251c36d>] tcp_transmit_skb net/ipv4/tcp_output.c:1057 [inline]
 [<ffffffff8251c36d>] tcp_write_xmit+0xf7d/0x4580 net/ipv4/tcp_output.c:2221
 [<ffffffff8251fa14>] __tcp_push_pending_frames+0xa4/0x250 net/ipv4/tcp_output.c:2402
 [<ffffffff824d449e>] tcp_push+0x3fe/0x5e0 net/ipv4/tcp.c:688
 [<ffffffff824e359b>] tcp_sendmsg+0x112b/0x2fd0 net/ipv4/tcp.c:1348
 [<ffffffff825952f3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:770
 [<ffffffff822a063b>] sock_sendmsg_nosec net/socket.c:648 [inline]
 [<ffffffff822a063b>] sock_sendmsg+0xbb/0x110 net/socket.c:658
 [<ffffffff822a08b3>] sock_write_iter+0x223/0x3b0 net/socket.c:856
 [<ffffffff81508347>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff81508347>] __vfs_write+0x3d7/0x580 fs/read_write.c:509
 [<ffffffff8150ab97>] vfs_write+0x187/0x520 fs/read_write.c:557
 [<ffffffff8150e9c9>] SYSC_write fs/read_write.c:604 [inline]
 [<ffffffff8150e9c9>] SyS_write+0xd9/0x1c0 fs/read_write.c:596
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=9300 comm=syz-executor.0
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=9326 comm=syz-executor.0
binder: BINDER_SET_CONTEXT_MGR already set
binder: 9596:9600 ioctl 40046207 0 returned -16
binder: 9596:9600 got transaction with invalid parent offset or type
binder: 9596:9600 transaction failed 29201/-22, size 40-8 line 3259
binder: undelivered TRANSACTION_ERROR: 29201
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=1793 sclass=netlink_xfrm_socket pig=10269 comm=syz-executor.0
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=1793 sclass=netlink_xfrm_socket pig=10281 comm=syz-executor.0