unregister_netdevice: waiting for syz_tun to become free. Usage count = 2
leaked reference.
 __netdev_tracker_alloc include/linux/netdevice.h:4049 [inline]
 netdev_hold include/linux/netdevice.h:4078 [inline]
 fib_check_nh_nongw net/ipv4/fib_semantics.c:1239 [inline]
 fib_check_nh+0xd15/0x1a60 net/ipv4/fib_semantics.c:1259
 fib_create_info+0x135c/0x2370 net/ipv4/fib_semantics.c:1558
 fib_table_insert+0xc2/0x1af0 net/ipv4/fib_trie.c:1217
 fib_magic+0x2ca/0x3b0 net/ipv4/fib_frontend.c:1118
 fib_add_ifaddr+0x3e2/0x5c0 net/ipv4/fib_frontend.c:1162
 fib_netdev_event+0x361/0x470 net/ipv4/fib_frontend.c:1500
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:455
 call_netdevice_notifiers_extack net/core/dev.c:2052 [inline]
 call_netdevice_notifiers net/core/dev.c:2066 [inline]
 __dev_notify_flags+0x1a7/0x310 net/core/dev.c:8715
 dev_change_flags+0xda/0x1a0 net/core/dev.c:8753
 do_setlink+0xbc7/0x29c0 net/core/rtnetlink.c:2837
 __rtnl_newlink net/core/rtnetlink.c:3614 [inline]
 rtnl_newlink+0x16e4/0x1f90 net/core/rtnetlink.c:3661
 rtnetlink_rcv_msg+0x863/0xfb0 net/core/rtnetlink.c:6158
 netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 __sys_sendto+0x497/0x650 net/socket.c:2153