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BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:276 [inline]
BUG: KASAN: use-after-free in dev_map_notification+0x4ef/0x5e0 kernel/bpf/devmap.c:406
Read of size 8 at addr ffff8800688b31a8 by task kworker/u8:0/5

CPU: 1 PID: 5 Comm: kworker/u8:0 Not tainted 4.13.0-rc5-next-20170815+ #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x24e/0x340 mm/kasan/report.c:409
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 __read_once_size include/linux/compiler.h:276 [inline]
 dev_map_notification+0x4ef/0x5e0 kernel/bpf/devmap.c:406
 notifier_call_chain+0x136/0x2c0 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+0x51/0x90 net/core/dev.c:1671
 call_netdevice_notifiers net/core/dev.c:1687 [inline]
 rollback_registered_many+0x91c/0xe80 net/core/dev.c:7141
 unregister_netdevice_many.part.107+0x87/0x420 net/core/dev.c:8190
 unregister_netdevice_many+0xbb/0x100 net/core/dev.c:8189
 sit_exit_net+0x470/0x690 net/ipv6/sit.c:1857
 ops_exit_list.isra.6+0xae/0x150 net/core/net_namespace.c:142
 cleanup_net+0x5c7/0xb50 net/core/net_namespace.c:483
 process_one_work+0xbf3/0x1bc0 kernel/workqueue.c:2098
 worker_thread+0x223/0x1860 kernel/workqueue.c:2233
 kthread+0x35e/0x430 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

Allocated by task 5265:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3725 [inline]
 __kmalloc+0x162/0x760 mm/slab.c:3734
 kmalloc include/linux/slab.h:498 [inline]
 bpf_map_area_alloc+0x2a/0x70 kernel/bpf/syscall.c:118
 dev_map_alloc+0x62c/0xa30 kernel/bpf/devmap.c:127
 find_and_alloc_map kernel/bpf/syscall.c:100 [inline]
 map_create kernel/bpf/syscall.c:324 [inline]
 SYSC_bpf kernel/bpf/syscall.c:1422 [inline]
 SyS_bpf+0xe1b/0x46a0 kernel/bpf/syscall.c:1403
 entry_SYSCALL_64_fastpath+0x1f/0xbe

Freed by task 3491:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xca/0x250 mm/slab.c:3820
 kvfree+0x36/0x60 mm/util.c:416
 bpf_map_area_free+0x15/0x20 kernel/bpf/syscall.c:128
 dev_map_free+0x452/0x5a0 kernel/bpf/devmap.c:191
 bpf_map_free_deferred+0xac/0xd0 kernel/bpf/syscall.c:208
 process_one_work+0xbf3/0x1bc0 kernel/workqueue.c:2098
 worker_thread+0x223/0x1860 kernel/workqueue.c:2233
 kthread+0x35e/0x430 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

The buggy address belongs to the object at ffff8800688b1a40
 which belongs to the cache kmalloc-8192 of size 8192
The buggy address is located 5992 bytes inside of
 8192-byte region [ffff8800688b1a40, ffff8800688b3a40)
The buggy address belongs to the page:
page:ffffea0001a22c00 count:1 mapcount:0 mapping:ffff8800688b1a40 index:0x0 compound_mapcount: 0
flags: 0x500000000008100(slab|head)
raw: 0500000000008100 ffff8800688b1a40 0000000000000000 0000000100000001
raw: ffffea00015d0c20 ffffea0001a4d320 ffff88003e802080 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8800688b3080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8800688b3100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8800688b3180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff8800688b3200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8800688b3280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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