netlink: 8 bytes leftover after parsing attributes in process `syz-executor.3'.
===============================
netlink: 8 bytes leftover after parsing attributes in process `syz-executor.3'.
[ 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
3 locks held by syz-executor.1/23248:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #1:  (rcu_read_lock){......}, at: [<ffffffff826e6c70>] __fib6_clean_all+0x0/0x220 net/ipv6/ip6_fib.c:1703
 #2:  (&tb->tb6_lock){++--..}, at: [<ffffffff826e6d50>] __fib6_clean_all+0xe0/0x220 net/ipv6/ip6_fib.c:1717

stack backtrace:
CPU: 1 PID: 23248 Comm: syz-executor.1 Not tainted 4.9.141+ #1
 ffff88018a497490 ffffffff81b42e79 ffff8801cb315f00 0000000000000000
 0000000000000002 ffffffff82cc2480 ffffed0031492ee0 ffff88018a4974c0
 ffffffff813fe948 ffff8801c6fa2e00 ffff88018a4976b0 ffff8801c6fa2e00
Call Trace:
 [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 [<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
 [<ffffffff826ef567>] fib6_clean_all+0x27/0x30 net/ipv6/ip6_fib.c:1729
 [<ffffffff826e4b51>] rt6_ifdown+0xa1/0x7f0 net/ipv6/route.c:2719
 [<ffffffff826bf2e0>] addrconf_ifdown+0xd0/0x1420 net/ipv6/addrconf.c:3569
 [<ffffffff826c74be>] addrconf_notify+0x8ee/0x2140 net/ipv6/addrconf.c:3493
 [<ffffffff811478d4>] notifier_call_chain+0xb4/0x1d0 kernel/notifier.c:93
 [<ffffffff81147a5d>] __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 [<ffffffff81147a5d>] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 [<ffffffff822f4a45>] call_netdevice_notifiers_info+0x55/0x70 net/core/dev.c:1647
 [<ffffffff823034e5>] call_netdevice_notifiers net/core/dev.c:1663 [inline]
 [<ffffffff823034e5>] rollback_registered_many+0x6e5/0xb50 net/core/dev.c:6860
 [<ffffffff82303a3e>] rollback_registered+0xee/0x1b0 net/core/dev.c:6901
 [<ffffffff8230d5fa>] unregister_netdevice_queue+0x1aa/0x230 net/core/dev.c:7888
 [<ffffffff81ed1e91>] unregister_netdevice include/linux/netdevice.h:2465 [inline]
 [<ffffffff81ed1e91>] __tun_detach+0x821/0xa00 drivers/net/tun.c:575
 [<ffffffff81ed20b4>] tun_detach drivers/net/tun.c:585 [inline]
 [<ffffffff81ed20b4>] tun_chr_close+0x44/0x60 drivers/net/tun.c:2392
 [<ffffffff81510293>] __fput+0x263/0x700 fs/file_table.c:208
 [<ffffffff815107b5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8113dc4c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff81003e49>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff81003e49>] exit_to_usermode_loop+0x129/0x150 arch/x86/entry/common.c:162
 [<ffffffff81005932>] prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 [<ffffffff81005932>] syscall_return_slowpath arch/x86/entry/common.c:263 [inline]
 [<ffffffff81005932>] do_syscall_64+0x3e2/0x550 arch/x86/entry/common.c:290
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
device lo entered promiscuous mode
device lo left promiscuous mode
EXT4-fs (sda1): Delayed block allocation failed for inode 16581 at logical offset 432 with max blocks 2048 with error 28
EXT4-fs (sda1): This should not happen!! Data will be lost

EXT4-fs (sda1): Total free blocks count 0
EXT4-fs (sda1): Free/Dirty block details
EXT4-fs (sda1): free_blocks=12060
EXT4-fs (sda1): dirty_blocks=5713
EXT4-fs (sda1): Block reservation details
EXT4-fs (sda1): i_reserved_data_blocks=3664
EXT4-fs (sda1): Delayed block allocation failed for inode 16581 at logical offset 2481 with max blocks 1615 with error 28
EXT4-fs (sda1): This should not happen!! Data will be lost

device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
qtaguid: iface_stat: create(lo): no inet dev
IPv6: ADDRCONF(NETDEV_UP): lo: link is not ready
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
qtaguid: iface_stat: create(lo): no inet dev
IPv6: ADDRCONF(NETDEV_UP): lo: link is not ready
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
qtaguid: iface_stat: create(lo): no inet dev
IPv6: ADDRCONF(NETDEV_UP): lo: link is not ready
device lo entered promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
device lo left promiscuous mode
qtaguid: iface_stat: create(lo): no inet dev
IPv6: ADDRCONF(NETDEV_UP): lo: link is not ready
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
qtaguid: iface_stat: create(lo): no inet dev
IPv6: ADDRCONF(NETDEV_UP): lo: link is not ready
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
device lo left promiscuous mode
qtaguid: iface_stat: create(lo): no inet dev
IPv6: ADDRCONF(NETDEV_UP): lo: link is not ready
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
qtaguid: iface_stat: create(lo): no inet dev
IPv6: ADDRCONF(NETDEV_UP): lo: link is not ready
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode
device lo left promiscuous mode
device lo entered promiscuous mode