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BUG: KASAN: use-after-free in __write_once_size include/linux/compiler.h:247 [inline]
BUG: KASAN: use-after-free in __hlist_del include/linux/list.h:632 [inline]
BUG: KASAN: use-after-free in hlist_del_rcu include/linux/rculist.h:340 [inline]
BUG: KASAN: use-after-free in nf_nat_cleanup_conntrack+0x1ca/0x1e0 net/netfilter/nf_nat_core.c:691
Write of size 8 at addr ffff8801c55a3478 by task kworker/u4:6/2183

CPU: 1 PID: 2183 Comm: kworker/u4:6 Not tainted 4.4.174+ #4
Workqueue: netns cleanup_net
 0000000000000000 cdf4e06548115634 ffff8801db707a48 ffffffff81aad1a1
 0000000000000001 ffffea00071568c0 ffff8801c55a3478 0000000000000008
 ffffffff82361100 ffff8801db707a80 ffffffff81490120 0000000000000001
Call Trace:
 <IRQ>  [<ffffffff81aad1a1>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ>  [<ffffffff81aad1a1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff81490120>] print_address_description+0x6f/0x21b mm/kasan/report.c:252
 [<ffffffff81490358>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81490358>] kasan_report mm/kasan/report.c:408 [inline]
 [<ffffffff81490358>] kasan_report.cold+0x8c/0x2be mm/kasan/report.c:393
 [<ffffffff81484f77>] __asan_report_store8_noabort+0x17/0x20 mm/kasan/report.c:434
 [<ffffffff823612ca>] __write_once_size include/linux/compiler.h:247 [inline]
 [<ffffffff823612ca>] __hlist_del include/linux/list.h:632 [inline]
 [<ffffffff823612ca>] hlist_del_rcu include/linux/rculist.h:340 [inline]
 [<ffffffff823612ca>] nf_nat_cleanup_conntrack+0x1ca/0x1e0 net/netfilter/nf_nat_core.c:691
 [<ffffffff8232d7b0>] __nf_ct_ext_destroy+0x140/0x2a0 net/netfilter/nf_conntrack_extend.c:40
 [<ffffffff8230e217>] nf_ct_ext_destroy include/net/netfilter/nf_conntrack_extend.h:80 [inline]
 [<ffffffff8230e217>] nf_conntrack_free+0x77/0x120 net/netfilter/nf_conntrack_core.c:904
 [<ffffffff823116f0>] destroy_conntrack+0x270/0x380 net/netfilter/nf_conntrack_core.c:365
 [<ffffffff822f6cd9>] nf_conntrack_destroy+0x99/0x1a0 net/netfilter/core.c:389
 [<ffffffff821eff3a>] nf_conntrack_put include/linux/skbuff.h:3377 [inline]
 [<ffffffff821eff3a>] skb_release_head_state+0x15a/0x210 net/core/skbuff.c:649
 [<ffffffff821fd0e6>] skb_release_all+0x16/0x60 net/core/skbuff.c:659
 [<ffffffff821fd257>] __kfree_skb net/core/skbuff.c:675 [inline]
 [<ffffffff821fd257>] kfree_skb+0xf7/0x400 net/core/skbuff.c:696
 [<ffffffff823b8e9a>] inet_frag_rbtree_purge+0xaa/0xf0 net/ipv4/ip_fragment.c:761
 [<ffffffff824e152f>] inet_frag_destroy+0x21f/0x2c0 net/ipv4/inet_fragment.c:156
 [<ffffffff823b8f14>] inet_frag_put include/net/inet_frag.h:124 [inline]
 [<ffffffff823b8f14>] ipq_put+0x34/0x40 net/ipv4/ip_fragment.c:164
 [<ffffffff823b954d>] ip_expire+0x14d/0x880 net/ipv4/ip_fragment.c:265
 [<ffffffff812582dd>] call_timer_fn+0x18d/0x850 kernel/time/timer.c:1185
 [<ffffffff81258ebf>] __run_timers kernel/time/timer.c:1261 [inline]
 [<ffffffff81258ebf>] run_timer_softirq+0x51f/0xb70 kernel/time/timer.c:1444
 [<ffffffff8271bb16>] __do_softirq+0x226/0xa3f kernel/softirq.c:273
 [<ffffffff82719cdc>] do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:956
 <EOI>  [<ffffffff810e1744>] do_softirq.part.0+0x54/0x60 kernel/softirq.c:317
 [<ffffffff810e181c>] do_softirq kernel/softirq.c:309 [inline]
 [<ffffffff810e181c>] __local_bh_enable_ip+0xcc/0xe0 kernel/softirq.c:170
 [<ffffffff8230eda8>] local_bh_enable include/linux/bottom_half.h:31 [inline]
 [<ffffffff8230eda8>] get_next_corpse net/netfilter/nf_conntrack_core.c:1403 [inline]
 [<ffffffff8230eda8>] nf_ct_iterate_cleanup+0x108/0x500 net/netfilter/nf_conntrack_core.c:1432
 [<ffffffff82315d3c>] nf_conntrack_cleanup_net_list+0x7c/0x300 net/netfilter/nf_conntrack_core.c:1522
 [<ffffffff82316ead>] nf_conntrack_pernet_exit+0x11d/0x170 net/netfilter/nf_conntrack_standalone.c:583
 [<ffffffff82217de5>] ops_exit_list.isra.0+0x105/0x160 net/core/net_namespace.c:137
 [<ffffffff8221ac16>] cleanup_net+0x3d6/0x860 net/core/net_namespace.c:452
 [<ffffffff81122c25>] process_one_work+0x825/0x1720 kernel/workqueue.c:2064
 [<ffffffff81124004>] worker_thread+0x4e4/0xf50 kernel/workqueue.c:2196
 [<ffffffff811342c3>] kthread+0x273/0x310 kernel/kthread.c:211
 [<ffffffff82718fc5>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537

The buggy address belongs to the page:
page:ffffea00071568c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c55a3300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8801c55a3380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8801c55a3400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff8801c55a3480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8801c55a3500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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