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BUG: KASAN: use-after-free in inet_frag_destroy_rcu+0xd9/0xe0 net/ipv4/inet_fragment.c:201
Read of size 8 at addr ffff8880a8cd9058 by task kworker/u4:4/2544

CPU: 1 PID: 2544 Comm: kworker/u4:4 Not tainted 5.2.0-rc1+ #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 inet_frag_destroy_rcu+0xd9/0xe0 net/ipv4/inet_fragment.c:201
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2092 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline]
 rcu_core+0xba5/0x1500 kernel/rcu/tree.c:2291
 __do_softirq+0x25c/0x94c kernel/softirq.c:293
 invoke_softirq kernel/softirq.c:374 [inline]
 irq_exit+0x180/0x1d0 kernel/softirq.c:414
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0x13b/0x550 arch/x86/kernel/apic/apic.c:1068
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:806
 </IRQ>
RIP: 0010:rcu_read_unlock include/linux/rcupdate.h:645 [inline]
RIP: 0010:inet_twsk_purge+0x53b/0x5f0 net/ipv4/inet_timewait_sock.c:299
Code: 01 e8 14 a5 6c fb e9 19 fe ff ff e8 6f 25 be fb e9 4b fc ff ff e8 15 8d 85 fb e8 70 9c 73 fb 31 ff 89 c3 89 c6 e8 45 8e 85 fb <84> db 0f 85 a9 fe ff ff e8 f8 8c 85 fb 48 c7 c2 60 e7 0a 88 be 85
RSP: 0018:ffff8880a1617b88 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff85eb176b
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff8880a1617bf8 R08: ffff8880a160e580 R09: ffffed1015d26be0
R10: ffffed1015d26bdf R11: ffff8880ae935efb R12: 000000000000000a
R13: 0000000000000001 R14: 000000000000e9d3 R15: dffffc0000000000
 tcpv6_net_exit_batch+0x1a/0x20 net/ipv6/tcp_ipv6.c:2045
 ops_exit_list.isra.0+0xfc/0x150 net/core/net_namespace.c:157
 cleanup_net+0x3fb/0x960 net/core/net_namespace.c:553
 process_one_work+0x989/0x1790 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x354/0x420 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 9205:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:489 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503
 kmem_cache_alloc_trace+0x151/0x750 mm/slab.c:3555
 kmalloc include/linux/slab.h:547 [inline]
 kzalloc include/linux/slab.h:742 [inline]
 fqdir_init include/net/inet_frag.h:115 [inline]
 nf_ct_net_init+0x4a/0x4d0 net/ipv6/netfilter/nf_conntrack_reasm.c:492
 ops_init+0xb3/0x410 net/core/net_namespace.c:130
 setup_net+0x2d3/0x740 net/core/net_namespace.c:316
 copy_net_ns+0x1df/0x340 net/core/net_namespace.c:439
 create_new_namespaces+0x400/0x7b0 kernel/nsproxy.c:107
 unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:206
 ksys_unshare+0x440/0x980 kernel/fork.c:2692
 __do_sys_unshare kernel/fork.c:2760 [inline]
 __se_sys_unshare kernel/fork.c:2758 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:2758
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 17:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
 __cache_free mm/slab.c:3432 [inline]
 kfree+0xcf/0x220 mm/slab.c:3755
 fqdir_rwork_fn+0x33/0x40 net/ipv4/inet_fragment.c:154
 process_one_work+0x989/0x1790 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x354/0x420 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8880a8cd9040
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of
 512-byte region [ffff8880a8cd9040, ffff8880a8cd9240)
The buggy address belongs to the page:
page:ffffea0002a33640 refcount:1 mapcount:0 mapping:ffff8880aa400940 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0002831448 ffffea0002a56888 ffff8880aa400940
raw: 0000000000000000 ffff8880a8cd9040 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a8cd8f00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a8cd8f80: 00 00 02 fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a8cd9000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                    ^
 ffff8880a8cd9080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a8cd9100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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