=====================================================
BUG: KMSAN: uninit-value in __ipv6_dev_mc_dec+0x6c9/0xd80 net/ipv6/mcast.c:974
 __ipv6_dev_mc_dec+0x6c9/0xd80 net/ipv6/mcast.c:974
 addrconf_leave_solict net/ipv6/addrconf.c:2191 [inline]
 __ipv6_ifa_notify+0xb17/0x1f50 net/ipv6/addrconf.c:6130
 addrconf_ifdown+0x19bc/0x2bc0 net/ipv6/addrconf.c:3840
 addrconf_notify+0x2f7/0x1d00
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0x122/0x2b0 kernel/notifier.c:391
 call_netdevice_notifiers_info net/core/dev.c:2002 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2014 [inline]
 call_netdevice_notifiers net/core/dev.c:2028 [inline]
 dev_close_many+0x70e/0xb20 net/core/dev.c:1603
 unregister_netdevice_many+0x8cd/0x3160 net/core/dev.c:11057
 default_device_exit_batch+0x6aa/0x6e0 net/core/dev.c:11610
 ops_exit_list net/core/net_namespace.c:171 [inline]
 cleanup_net+0xf0a/0x1b20 net/core/net_namespace.c:593
 process_one_work+0xdb9/0x1820 kernel/workqueue.c:2298
 worker_thread+0x10bc/0x21f0 kernel/workqueue.c:2445
 kthread+0x721/0x850 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

Local variable maddr.i created at:
 addrconf_leave_solict net/ipv6/addrconf.c:2185 [inline]
 __ipv6_ifa_notify+0x8c1/0x1f50 net/ipv6/addrconf.c:6130
 addrconf_ifdown+0x19bc/0x2bc0 net/ipv6/addrconf.c:3840

CPU: 0 PID: 39 Comm: kworker/u4:1 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
=====================================================