===============================
[ INFO: suspicious RCU usage. ]
4.9.112-g9e79039 #59 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
3 locks held by syz-executor5/11683:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff830ba45b>] rtnl_lock net/core/rtnetlink.c:70 [inline]
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff830ba45b>] rtnetlink_rcv+0x1b/0x40 net/core/rtnetlink.c:4064
 #1:  (rcu_read_lock){......}, at: [<ffffffff835a7c50>] __fib6_clean_all+0x0/0x220 net/ipv6/ip6_fib.c:1703
 #2:  (&tb->tb6_lock){++--..}, at: [<ffffffff835a7d30>] __fib6_clean_all+0xe0/0x220 net/ipv6/ip6_fib.c:1717

stack backtrace:
CPU: 0 PID: 11683 Comm: syz-executor5 Not tainted 4.9.112-g9e79039 #59
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801cccb6848 ffffffff81eb3249 ffff8801c9fbc800 0000000000000000
 0000000000000002 ffffffff84166880 ffffed0039996d58 ffff8801cccb6878
 ffffffff814260f0 ffff8801b8077dc0 ffff8801cccb6a70 ffff8801b8077dc0
Call Trace:
 [<ffffffff81eb3249>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3249>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff814260f0>] lockdep_rcu_suspicious.cold.48+0x110/0x141 kernel/locking/lockdep.c:4455
 [<ffffffff835ae1e3>] fib6_del+0x773/0xa20 net/ipv6/ip6_fib.c:1470
 [<ffffffff835ae6b0>] fib6_clean_node+0x220/0x4c0 net/ipv6/ip6_fib.c:1657
 [<ffffffff835a5995>] fib6_walk_continue+0x3e5/0x640 net/ipv6/ip6_fib.c:1583
 [<ffffffff835a7ac9>] fib6_walk+0xd9/0x150 net/ipv6/ip6_fib.c:1628
 [<ffffffff835a7c13>] fib6_clean_tree+0xd3/0x110 net/ipv6/ip6_fib.c:1702
 [<ffffffff835a7d49>] __fib6_clean_all+0xf9/0x220 net/ipv6/ip6_fib.c:1718
 [<ffffffff835ae977>] fib6_clean_all+0x27/0x30 net/ipv6/ip6_fib.c:1729
 [<ffffffff835a4391>] rt6_ifdown+0xa1/0x7f0 net/ipv6/route.c:2716
 [<ffffffff8357efd0>] addrconf_ifdown+0xd0/0x10e0 net/ipv6/addrconf.c:3569
 [<ffffffff83586ad8>] addrconf_notify+0x7f8/0x2160 net/ipv6/addrconf.c:3493
 [<ffffffff811a18d4>] notifier_call_chain+0xb4/0x1d0 kernel/notifier.c:93
 [<ffffffff811a1a5d>] __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 [<ffffffff811a1a5d>] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 [<ffffffff83068f85>] call_netdevice_notifiers_info+0x55/0x70 net/core/dev.c:1647
 [<ffffffff8308d1cd>] call_netdevice_notifiers net/core/dev.c:1663 [inline]
 [<ffffffff8308d1cd>] __dev_notify_flags+0x19d/0x270 net/core/dev.c:6515
 [<ffffffff8308e343>] dev_change_flags+0xf3/0x140 net/core/dev.c:6546
 [<ffffffff830bb90f>] do_setlink+0x9af/0x2ef0 net/core/rtnetlink.c:2027
 [<ffffffff830c8c00>] rtnl_group_changelink net/core/rtnetlink.c:2414 [inline]
 [<ffffffff830c8c00>] rtnl_newlink+0xbd0/0x1550 net/core/rtnetlink.c:2562
 [<ffffffff830c9a1c>] rtnetlink_rcv_msg+0x49c/0x650 net/core/rtnetlink.c:4059
 [<ffffffff831d2565>] netlink_rcv_skb+0x145/0x370 net/netlink/af_netlink.c:2358
 [<ffffffff830ba46a>] rtnetlink_rcv+0x2a/0x40 net/core/rtnetlink.c:4065
 [<ffffffff831d1118>] netlink_unicast_kernel net/netlink/af_netlink.c:1278 [inline]
 [<ffffffff831d1118>] netlink_unicast+0x4d8/0x6f0 net/netlink/af_netlink.c:1304
 [<ffffffff831d1ac5>] netlink_sendmsg+0x795/0xc30 net/netlink/af_netlink.c:1852
 [<ffffffff83016fcc>] sock_sendmsg_nosec net/socket.c:635 [inline]
 [<ffffffff83016fcc>] sock_sendmsg+0xcc/0x110 net/socket.c:645
 [<ffffffff83018a6c>] ___sys_sendmsg+0x6fc/0x840 net/socket.c:1969
 [<ffffffff8301aad9>] __sys_sendmsg+0xd9/0x190 net/socket.c:2003
 [<ffffffff8301abbd>] SYSC_sendmsg net/socket.c:2014 [inline]
 [<ffffffff8301abbd>] SyS_sendmsg+0x2d/0x50 net/socket.c:2010
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9f53>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=26660 sclass=netlink_xfrm_socket pig=11741 comm=syz-executor0
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=26660 sclass=netlink_xfrm_socket pig=11746 comm=syz-executor0
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=26660 sclass=netlink_xfrm_socket pig=11769 comm=syz-executor0
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=26660 sclass=netlink_xfrm_socket pig=11781 comm=syz-executor0
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=26660 sclass=netlink_xfrm_socket pig=11794 comm=syz-executor0
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=26660 sclass=netlink_xfrm_socket pig=11803 comm=syz-executor1
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=26660 sclass=netlink_xfrm_socket pig=11806 comm=syz-executor0
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=26660 sclass=netlink_xfrm_socket pig=11808 comm=syz-executor1
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=26660 sclass=netlink_xfrm_socket pig=11827 comm=syz-executor0
SELinux: unrecognized netlink message: protocol=6 nlmsg_type=26660 sclass=netlink_xfrm_socket pig=11830 comm=syz-executor1