netlink: 4 bytes leftover after parsing attributes in process `syz-executor1'.
==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0xf1/0x100 lib/list_debug.c:51
Read of size 8 at addr ffff8881d7288bb0 by task kworker/u4:0/7

CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 4.20.0-rc6-next-20181210+ #164
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x244/0x39d lib/dump_stack.c:113
 print_address_description.cold.4+0x9/0x1ff mm/kasan/report.c:187
 kasan_report.cold.5+0x1b/0x39 mm/kasan/report.c:317
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
 __list_del_entry_valid+0xf1/0x100 lib/list_debug.c:51
 __list_del_entry include/linux/list.h:117 [inline]
 list_del_init include/linux/list.h:159 [inline]
 neigh_mark_dead+0x13b/0x410 net/core/neighbour.c:125
 neigh_flush_dev+0x3a1/0x960 net/core/neighbour.c:290
 __neigh_ifdown+0x44/0x2c0 net/core/neighbour.c:328
 neigh_ifdown+0x1f/0x30 net/core/neighbour.c:345
 rt6_disable_ip+0x5b8/0x720 net/ipv6/route.c:4046
 addrconf_ifdown+0x168/0x1650 net/ipv6/addrconf.c:3669
 addrconf_notify+0x6de/0x2770 net/ipv6/addrconf.c:3594
 notifier_call_chain+0x17e/0x380 kernel/notifier.c:93
 __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1737
 call_netdevice_notifiers_extack net/core/dev.c:1749 [inline]
 call_netdevice_notifiers net/core/dev.c:1763 [inline]
 dev_close_many+0x443/0x8b0 net/core/dev.c:1507
 rollback_registered_many+0x543/0x1260 net/core/dev.c:8041
 unregister_netdevice_many+0xfa/0x4c0 net/core/dev.c:9169
 default_device_exit_batch+0x43a/0x540 net/core/dev.c:9638
 ops_exit_list.isra.5+0x105/0x160 net/core/net_namespace.c:156
 cleanup_net+0x555/0xb10 net/core/net_namespace.c:551
 process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
 kthread+0x35a/0x440 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 6057:
 save_stack+0x43/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 kasan_kmalloc+0xcb/0xd0 mm/kasan/common.c:482
 __do_kmalloc mm/slab.c:3709 [inline]
 __kmalloc+0x15d/0x760 mm/slab.c:3718
 kmalloc include/linux/slab.h:550 [inline]
 kzalloc include/linux/slab.h:740 [inline]
 neigh_alloc net/core/neighbour.c:375 [inline]
 ___neigh_create+0x13fc/0x2600 net/core/neighbour.c:553
 __neigh_create+0x30/0x40 net/core/neighbour.c:640
 ip6_finish_output2+0xa64/0x2940 net/ipv6/ip6_output.c:117
 ip6_finish_output+0x58c/0xc60 net/ipv6/ip6_output.c:154
 NF_HOOK_COND include/linux/netfilter.h:278 [inline]
 ip6_output+0x232/0x9d0 net/ipv6/ip6_output.c:171
 dst_output include/net/dst.h:444 [inline]
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ndisc_send_skb+0x1005/0x1560 net/ipv6/ndisc.c:491
 ndisc_send_rs+0x134/0x6e0 net/ipv6/ndisc.c:685
 addrconf_rs_timer+0x314/0x690 net/ipv6/addrconf.c:3840
 call_timer_fn+0x272/0x920 kernel/time/timer.c:1325
 expire_timers kernel/time/timer.c:1362 [inline]
 __run_timers+0x7e5/0xc70 kernel/time/timer.c:1681
 run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1694
 __do_softirq+0x308/0xb7e kernel/softirq.c:292

Freed by task 0:
 save_stack+0x43/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:444
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:452
 __cache_free mm/slab.c:3485 [inline]
 kfree+0xcf/0x230 mm/slab.c:3804
 __rcu_reclaim kernel/rcu/rcu.h:233 [inline]
 rcu_do_batch kernel/rcu/tree.c:2452 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
 rcu_process_callbacks+0xd91/0x15f0 kernel/rcu/tree.c:2754
 __do_softirq+0x308/0xb7e kernel/softirq.c:292

The buggy address belongs to the object at ffff8881d7288940
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 624 bytes inside of
 1024-byte region [ffff8881d7288940, ffff8881d7288d40)
The buggy address belongs to the page:
page:ffffea00075ca200 count:1 mapcount:0 mapping:ffff8881da800ac0 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000010200(slab|head)
raw: 02fffc0000010200 ffffea0007050c08 ffffea0007038888 ffff8881da800ac0
raw: 0000000000000000 ffff8881d7288040 0000000100000007 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881d7288a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881d7288b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881d7288b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff8881d7288c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881d7288c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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