unregister_netdevice: waiting for syz_tun to become free. Usage count = 4
ref_tracker: syz_tun@ffff8880254685b8 has 1/3 users at
     __netdev_tracker_alloc include/linux/netdevice.h:4110 [inline]
     netdev_hold include/linux/netdevice.h:4139 [inline]
     dst_init+0xd9/0x480 net/core/dst.c:52
     dst_alloc+0x12e/0x170 net/core/dst.c:94
     rt_dst_alloc net/ipv4/route.c:1662 [inline]
     __mkroute_output net/ipv4/route.c:2626 [inline]
     ip_route_output_key_hash_rcu+0x14f6/0x2370 net/ipv4/route.c:2848
     ip_route_output_key_hash+0x1f3/0x330 net/ipv4/route.c:2677
     __ip_route_output_key include/net/route.h:134 [inline]
     ip_route_output_flow+0x2a/0x150 net/ipv4/route.c:2905
     ip_route_output_key include/net/route.h:150 [inline]
     sctp_v4_get_dst+0x400/0x1230 net/sctp/protocol.c:452
     sctp_transport_route+0x10b/0x2c0 net/sctp/transport.c:457
     sctp_assoc_add_peer+0x650/0x1390 net/sctp/associola.c:663
     sctp_connect_new_asoc+0x323/0x6a0 net/sctp/socket.c:1099
     sctp_sendmsg_new_asoc net/sctp/socket.c:1691 [inline]
     sctp_sendmsg+0x1575/0x28c0 net/sctp/socket.c:2002
     sock_sendmsg_nosec net/socket.c:730 [inline]
     __sock_sendmsg net/socket.c:745 [inline]
     ____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
     ___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
     __sys_sendmsg net/socket.c:2677 [inline]
     __do_sys_sendmsg net/socket.c:2686 [inline]
     __se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
     do_syscall_x64 arch/x86/entry/common.c:46 [inline]
     do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
     entry_SYSCALL_64_after_hwframe+0x68/0xd2

ref_tracker: syz_tun@ffff8880254685b8 has 1/3 users at
     __netdev_tracker_alloc include/linux/netdevice.h:4110 [inline]
     netdev_hold include/linux/netdevice.h:4139 [inline]
     dst_init+0xd9/0x480 net/core/dst.c:52
     dst_alloc+0x12e/0x170 net/core/dst.c:94
     rt_dst_alloc net/ipv4/route.c:1662 [inline]
     __mkroute_output net/ipv4/route.c:2626 [inline]
     ip_route_output_key_hash_rcu+0x14f6/0x2370 net/ipv4/route.c:2848
     ip_route_output_key_hash+0x1f3/0x330 net/ipv4/route.c:2677
     icmp_route_lookup+0x41f/0xa20 net/ipv4/icmp.c:506
     __icmp_send+0xef1/0x1420 net/ipv4/icmp.c:758
     ipv4_send_dest_unreach net/ipv4/route.c:1263 [inline]
     ipv4_link_failure+0x657/0xa40 net/ipv4/route.c:1270
     dst_link_failure include/net/dst.h:437 [inline]
     arp_error_report+0x112/0x160 net/ipv4/arp.c:296
     neigh_invalidate+0x22c/0x450 net/core/neighbour.c:1064
     neigh_timer_handler+0x914/0xff0 net/core/neighbour.c:1151
     call_timer_fn+0x189/0x540 kernel/time/timer.c:1701
     expire_timers kernel/time/timer.c:1752 [inline]
     __run_timers+0x542/0x800 kernel/time/timer.c:2023
     run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
     handle_softirqs+0x280/0x820 kernel/softirq.c:578
     __do_softirq kernel/softirq.c:612 [inline]
     invoke_softirq kernel/softirq.c:452 [inline]
     __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
     irq_exit_rcu+0x9/0x20 kernel/softirq.c:673

ref_tracker: syz_tun@ffff8880254685b8 has 1/3 users at
     __netdev_tracker_alloc include/linux/netdevice.h:4110 [inline]
     netdev_hold include/linux/netdevice.h:4139 [inline]
     fib_check_nh_nongw net/ipv4/fib_semantics.c:1239 [inline]
     fib_check_nh+0xd23/0x1a70 net/ipv4/fib_semantics.c:1259
     fib_create_info+0x142c/0x2460 net/ipv4/fib_semantics.c:1557
     fib_table_insert+0xc6/0x1b20 net/ipv4/fib_trie.c:1217
     fib_magic+0x2e5/0x3c0 net/ipv4/fib_frontend.c:1118
     fib_add_ifaddr+0x38d/0x5e0 net/ipv4/fib_frontend.c:1155
     fib_netdev_event+0x389/0x490 net/ipv4/fib_frontend.c:1500
     notifier_call_chain+0x197/0x380 kernel/notifier.c:93
     call_netdevice_notifiers_extack net/core/dev.c:2077 [inline]
     call_netdevice_notifiers net/core/dev.c:2091 [inline]
     __dev_notify_flags+0x1aa/0x310 net/core/dev.c:8762
     dev_change_flags+0xe8/0x1a0 net/core/dev.c:8800
     do_setlink+0xc58/0x4130 net/core/rtnetlink.c:2908
     __rtnl_newlink net/core/rtnetlink.c:3706 [inline]
     rtnl_newlink+0x17da/0x20a0 net/core/rtnetlink.c:3753
     rtnetlink_rcv_msg+0x869/0xfa0 net/core/rtnetlink.c:6475
     netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
     netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
     netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
     netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
     sock_sendmsg_nosec net/socket.c:730 [inline]
     __sock_sendmsg net/socket.c:745 [inline]
     __sys_sendto+0x4a9/0x6b0 net/socket.c:2200