unregister_netdevice: waiting for syz_tun to become free. Usage count = 3
ref_tracker: syz_tun@ffff88805ee245b8 has 1/2 users at
     __netdev_tracker_alloc include/linux/netdevice.h:4159 [inline]
     netdev_tracker_alloc include/linux/netdevice.h:4171 [inline]
     netdev_get_by_index+0x79/0xa0 net/core/dev.c:911
     fib6_nh_init+0x1ff/0x1fe0 net/ipv6/route.c:3587
     ip6_route_info_create+0x96c/0x1260 net/ipv6/route.c:3857
     addrconf_f6i_alloc+0x1fa/0x440 net/ipv6/route.c:4633
     fixup_permanent_addr net/ipv6/addrconf.c:3585 [inline]
     addrconf_permanent_addr+0x294/0xa50 net/ipv6/addrconf.c:3624
     addrconf_notify+0x996/0x1010 net/ipv6/addrconf.c:3696
     notifier_call_chain+0x18f/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+0x1ab/0x310 net/core/dev.c:8786
     dev_change_flags+0xde/0x1a0 net/core/dev.c:8824
     do_setlink+0xb69/0x3f40 net/core/rtnetlink.c:2917
     __rtnl_newlink net/core/rtnetlink.c:3715 [inline]
     rtnl_newlink+0x1848/0x2170 net/core/rtnetlink.c:3762
     rtnetlink_rcv_msg+0x843/0xf90 net/core/rtnetlink.c:6484
     netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
     netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
     netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
     netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
     sock_sendmsg_nosec net/socket.c:730 [inline]
     __sock_sendmsg net/socket.c:745 [inline]
     __sys_sendto+0x4a9/0x6b0 net/socket.c:2201

ref_tracker: syz_tun@ffff88805ee245b8 has 1/2 users at
     __netdev_tracker_alloc include/linux/netdevice.h:4159 [inline]
     netdev_hold include/linux/netdevice.h:4188 [inline]
     ipv6_add_dev+0x407/0x11f0 net/ipv6/addrconf.c:402
     addrconf_notify+0x67b/0x1010 net/ipv6/addrconf.c:3652
     notifier_call_chain+0x18f/0x380 kernel/notifier.c:93
     call_netdevice_notifiers_extack net/core/dev.c:2077 [inline]
     call_netdevice_notifiers net/core/dev.c:2091 [inline]
     register_netdevice+0x1670/0x1ba0 net/core/dev.c:10375
     tun_set_iff+0x82b/0xea0 drivers/net/tun.c:2876
     __tun_chr_ioctl+0x7e0/0x2070 drivers/net/tun.c:3145
     vfs_ioctl fs/ioctl.c:51 [inline]
     __do_sys_ioctl fs/ioctl.c:871 [inline]
     __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
     do_syscall_x64 arch/x86/entry/common.c:46 [inline]
     do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
     entry_SYSCALL_64_after_hwframe+0x68/0xd2