=====================================================
BUG: KMSAN: use-after-free in ip6_ignore_linkdown include/net/addrconf.h:402 [inline]
BUG: KMSAN: use-after-free in find_match+0x317/0x1480 net/ipv6/route.c:749
CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 5.6.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x220 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 ip6_ignore_linkdown include/net/addrconf.h:402 [inline]
 find_match+0x317/0x1480 net/ipv6/route.c:749
 __find_rr_leaf+0x3f9/0x1160 net/ipv6/route.c:837
 find_rr_leaf net/ipv6/route.c:858 [inline]
 rt6_select net/ipv6/route.c:902 [inline]
 fib6_table_lookup+0x586/0x1420 net/ipv6/route.c:2170
 ip6_pol_route+0x203/0x2960 net/ipv6/route.c:2206
 ip6_pol_route_input+0x123/0x140 net/ipv6/route.c:2264
 fib6_rule_lookup+0x38f/0xa10 net/ipv6/fib6_rules.c:114
 ip6_route_input_lookup net/ipv6/route.c:2276 [inline]
 ip6_route_input+0xb9d/0xcf0 net/ipv6/route.c:2445
 ip6_rcv_finish_core+0x1f9/0x470 net/ipv6/ip6_input.c:63
 ip6_rcv_finish net/ipv6/ip6_input.c:74 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 ipv6_rcv+0x628/0x710 net/ipv6/ip6_input.c:306
 __netif_receive_skb_one_core net/core/dev.c:5198 [inline]
 __netif_receive_skb net/core/dev.c:5312 [inline]
 process_backlog+0xa41/0x1410 net/core/dev.c:6144
 napi_poll net/core/dev.c:6582 [inline]
 net_rx_action+0x786/0x1aa0 net/core/dev.c:6650
 __do_softirq+0x311/0x83d kernel/softirq.c:293
 run_ksoftirqd+0x25/0x40 kernel/softirq.c:607
 smpboot_thread_fn+0x493/0x980 kernel/smpboot.c:165
 kthread+0x4b5/0x4f0 kernel/kthread.c:256
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:353

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
 kmsan_slab_free+0x6e/0xb0 mm/kmsan/kmsan_hooks.c:107
 slab_free_freelist_hook mm/slub.c:1477 [inline]
 slab_free mm/slub.c:3040 [inline]
 kfree+0x565/0x30a0 mm/slub.c:3993
 snmp6_free_dev net/ipv6/addrconf_core.c:224 [inline]
 in6_dev_finish_destroy_rcu+0x64/0x120 net/ipv6/addrconf_core.c:233
 rcu_do_batch kernel/rcu/tree.c:2186 [inline]
 rcu_core+0xb8a/0x19f0 kernel/rcu/tree.c:2410
 rcu_core_si+0xe/0x10 kernel/rcu/tree.c:2419
 __do_softirq+0x311/0x83d kernel/softirq.c:293
=====================================================