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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:202 [inline]
BUG: KASAN: use-after-free in xfrm6_tunnel_destroy+0x4df/0x570 net/ipv6/xfrm6_tunnel.c:303
Read of size 8 at addr ffff8801c7dc9618 by task kworker/1:1/22

CPU: 1 PID: 22 Comm: kworker/1:1 Not tainted 4.9.168+ #40
Workqueue: events xfrm_state_gc_task
 ffff8801d9c2fa60 ffffffff81b4f5d1 0000000000000000 ffffea00071f7200
 ffff8801c7dc9618 0000000000000008 ffffffff82772c4f ffff8801d9c2fa98
 ffffffff81506898 0000000000000000 ffff8801c7dc9618 ffff8801c7dc9618
Call Trace:
 [<000000006b13ca42>] __dump_stack lib/dump_stack.c:15 [inline]
 [<000000006b13ca42>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<00000000d722bf75>] print_address_description+0x6f/0x23a mm/kasan/report.c:256
 [<00000000654bceaf>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<00000000654bceaf>] kasan_report mm/kasan/report.c:412 [inline]
 [<00000000654bceaf>] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:397
 [<0000000017b2556d>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<0000000040c6946f>] __read_once_size include/linux/compiler.h:243 [inline]
 [<0000000040c6946f>] net_generic include/net/netns/generic.h:40 [inline]
 [<0000000040c6946f>] xfrm6_tunnel_pernet net/ipv6/xfrm6_tunnel.c:50 [inline]
 [<0000000040c6946f>] xfrm6_tunnel_free_spi net/ipv6/xfrm6_tunnel.c:202 [inline]
 [<0000000040c6946f>] xfrm6_tunnel_destroy+0x4df/0x570 net/ipv6/xfrm6_tunnel.c:303
 [<00000000afa049ab>] xfrm_state_gc_destroy net/xfrm/xfrm_state.c:368 [inline]
 [<00000000afa049ab>] xfrm_state_gc_task+0x3b9/0x520 net/xfrm/xfrm_state.c:388
 [<00000000f3a16349>] process_one_work+0x88b/0x1600 kernel/workqueue.c:2114
 [<00000000afbb6845>] worker_thread+0x5df/0x11d0 kernel/workqueue.c:2251
 [<00000000cba7c17d>] kthread+0x278/0x310 kernel/kthread.c:211
 [<000000006663aa7c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

Allocated by task 2189:
 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.0+0x62/0xf0 mm/kasan/kasan.c:609
 kasan_kmalloc+0xb7/0xd0 mm/kasan/kasan.c:594
 kasan_slab_alloc+0xf/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+0xfa/0x340 net/core/net_namespace.c:398
 create_new_namespaces+0x37c/0x7a0 kernel/nsproxy.c:106
 unshare_nsproxy_namespaces+0xab/0x1e0 kernel/nsproxy.c:205
 SYSC_unshare kernel/fork.c:2276 [inline]
 SyS_unshare+0x305/0x6f0 kernel/fork.c:2226
 do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Freed by task 64:
 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+0xb0/0x190 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+0x68/0x80 net/core/net_namespace.c:381
 cleanup_net+0x505/0x8a0 net/core/net_namespace.c:491
 process_one_work+0x88b/0x1600 kernel/workqueue.c:2114
 worker_thread+0x5df/0x11d0 kernel/workqueue.c:2251
 kthread+0x278/0x310 kernel/kthread.c:211
 ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373

The buggy address belongs to the object at ffff8801c7dc8000
 which belongs to the cache net_namespace of size 7552
The buggy address is located 5656 bytes inside of
 7552-byte region [ffff8801c7dc8000, ffff8801c7dc9d80)
The buggy address belongs to the page:
page:ffffea00071f7200 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
flags: 0x4000000000010200(slab|head)
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c7dc9500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c7dc9580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801c7dc9600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff8801c7dc9680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c7dc9700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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