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BUG: KASAN: slab-out-of-bounds in __list_del_entry_valid+0xf1/0x100 lib/list_debug.c:51
Read of size 8 at addr ffff8881bcba9930 by task kworker/0:2/2937

CPU: 0 PID: 2937 Comm: kworker/0:2 Not tainted 4.20.0-rc6+ #336
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_power_efficient neigh_periodic_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x244/0x39d lib/dump_stack.c:113
 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 __list_del_entry_valid+0xf1/0x100 lib/list_debug.c:51
 __list_del_entry include/linux/list.h:117 [inline]
 list_del_init include/linux/list.h:159 [inline]
 neigh_mark_dead+0x13b/0x410 net/core/neighbour.c:125
 neigh_periodic_work+0x89a/0xc30 net/core/neighbour.c:905
 process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
 kthread+0x35a/0x440 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 6115:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x730 mm/slab.c:3554
 getname_flags+0xd0/0x590 fs/namei.c:140
 getname fs/namei.c:211 [inline]
 user_path_mountpoint_at+0x27/0x40 fs/namei.c:2747
 ksys_umount+0x1c5/0x12d0 fs/namespace.c:1645
 __do_sys_umount fs/namespace.c:1671 [inline]
 __se_sys_umount fs/namespace.c:1669 [inline]
 __x64_sys_umount+0x54/0x80 fs/namespace.c:1669
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6115:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x83/0x290 mm/slab.c:3760
 putname+0xf2/0x130 fs/namei.c:261
 filename_mountpoint+0x35a/0x460 fs/namei.c:2725
 user_path_mountpoint_at+0x37/0x40 fs/namei.c:2747
 ksys_umount+0x1c5/0x12d0 fs/namespace.c:1645
 __do_sys_umount fs/namespace.c:1671 [inline]
 __se_sys_umount fs/namespace.c:1669 [inline]
 __x64_sys_umount+0x54/0x80 fs/namespace.c:1669
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881bcba8400
 which belongs to the cache names_cache of size 4096
The buggy address is located 1328 bytes to the right of
 4096-byte region [ffff8881bcba8400, ffff8881bcba9400)
The buggy address belongs to the page:
page:ffffea0006f2ea00 count:1 mapcount:0 mapping:ffff8881da980e00 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000010200(slab|head)
raw: 02fffc0000010200 ffffea0007497088 ffffea0007358c88 ffff8881da980e00
raw: 0000000000000000 ffff8881bcba8400 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881bcba9800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881bcba9880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881bcba9900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                     ^
 ffff8881bcba9980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881bcba9a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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