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BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:243 [inline]
BUG: KASAN: use-after-free in net_generic include/net/netns/generic.h:40 [inline]
BUG: KASAN: use-after-free in xfrm6_tunnel_pernet net/ipv6/xfrm6_tunnel.c:50 [inline]
BUG: KASAN: use-after-free in xfrm6_tunnel_free_spi net/ipv6/xfrm6_tunnel.c:199 [inline]
BUG: KASAN: use-after-free in xfrm6_tunnel_destroy+0x5a5/0x630 net/ipv6/xfrm6_tunnel.c:300
Read of size 8 at addr ffff8801cfd81618 by task kworker/1:1/22

CPU: 1 PID: 22 Comm: kworker/1:1 Not tainted 4.9.135+ #61
Workqueue: events xfrm_state_gc_task
 ffff8801d9c2faa0 ffffffff81b36bf9 ffffea00073f6000 ffff8801cfd81618
 0000000000000000 ffff8801cfd81618 ffff8801d8cbd9a8 ffff8801d9c2fad8
 ffffffff815009ad ffff8801cfd81618 0000000000000008 0000000000000000
Call Trace:
 [<ffffffff81b36bf9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b36bf9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff815009ad>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff81500db7>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff81500db7>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff814f2fc4>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<ffffffff8276ad85>] __read_once_size include/linux/compiler.h:243 [inline]
 [<ffffffff8276ad85>] net_generic include/net/netns/generic.h:40 [inline]
 [<ffffffff8276ad85>] xfrm6_tunnel_pernet net/ipv6/xfrm6_tunnel.c:50 [inline]
 [<ffffffff8276ad85>] xfrm6_tunnel_free_spi net/ipv6/xfrm6_tunnel.c:199 [inline]
 [<ffffffff8276ad85>] xfrm6_tunnel_destroy+0x5a5/0x630 net/ipv6/xfrm6_tunnel.c:300
 [<ffffffff8263c0fd>] xfrm_state_gc_destroy net/xfrm/xfrm_state.c:368 [inline]
 [<ffffffff8263c0fd>] xfrm_state_gc_task+0x3ad/0x510 net/xfrm/xfrm_state.c:388
 [<ffffffff81130d61>] process_one_work+0x831/0x1530 kernel/workqueue.c:2092
 [<ffffffff81131b36>] worker_thread+0xd6/0x1140 kernel/workqueue.c:2226
 [<ffffffff811428dd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff8280addc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Allocated by task 2086:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack mm/kasan/kasan.c:505 [inline]
 set_track mm/kasan/kasan.c:517 [inline]
 kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:609
 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:594
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:547
 slab_post_alloc_hook mm/slab.h:417 [inline]
 slab_alloc_node mm/slub.c:2715 [inline]
 slab_alloc mm/slub.c:2723 [inline]
 kmem_cache_alloc+0xd5/0x2b0 mm/slub.c:2728
 kmem_cache_zalloc include/linux/slab.h:626 [inline]
 net_alloc net/core/net_namespace.c:358 [inline]
 copy_net_ns+0xf5/0x330 net/core/net_namespace.c:398
 create_new_namespaces+0x501/0x760 kernel/nsproxy.c:106
 unshare_nsproxy_namespaces+0xa5/0x1d0 kernel/nsproxy.c:205
 SYSC_unshare kernel/fork.c:2263 [inline]
 SyS_unshare+0x319/0x710 kernel/fork.c:2213
 do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Freed by task 2185:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack mm/kasan/kasan.c:505 [inline]
 set_track mm/kasan/kasan.c:517 [inline]
 kasan_slab_free+0xac/0x190 mm/kasan/kasan.c:582
 slab_free_hook mm/slub.c:1355 [inline]
 slab_free_freelist_hook mm/slub.c:1377 [inline]
 slab_free mm/slub.c:2958 [inline]
 kmem_cache_free+0xbe/0x310 mm/slub.c:2980
 net_free net/core/net_namespace.c:374 [inline]
 net_drop_ns+0x62/0x80 net/core/net_namespace.c:381
 cleanup_net+0x627/0x8b0 net/core/net_namespace.c:491
 process_one_work+0x831/0x1530 kernel/workqueue.c:2092
 worker_thread+0xd6/0x1140 kernel/workqueue.c:2226
 kthread+0x26d/0x300 kernel/kthread.c:211
 ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

The buggy address belongs to the object at ffff8801cfd80000
 which belongs to the cache net_namespace of size 7552
The buggy address is located 5656 bytes inside of
 7552-byte region [ffff8801cfd80000, ffff8801cfd81d80)
The buggy address belongs to the page:
page:ffffea00073f6000 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
flags: 0x4000000000004080(slab|head)
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cfd81500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801cfd81580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801cfd81600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff8801cfd81680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801cfd81700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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