attempt to access beyond end of device
unknown-block(7,0): rw=0, want=0, limit=256
attempt to access beyond end of device
unknown-block(7,0): rw=0, want=0, limit=256
==================================================================
BUG: KASAN: slab-out-of-bounds in memset include/linux/string.h:326 [inline]
BUG: KASAN: slab-out-of-bounds in __unwind_start+0x2d/0x330 arch/x86/kernel/unwind_frame.c:389
Write of size 88 at addr ffff8801cac87e98 by task loop0/14671

CPU: 1 PID: 14671 Comm: loop0 Not tainted 4.15.0-rc2-next-20171206+ #60
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:

Allocated by task 3669:
 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
 kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3614
 kmalloc include/linux/slab.h:516 [inline]
 kzalloc include/linux/slab.h:705 [inline]
 lockdep_init_task+0x187/0x210 kernel/locking/lockdep.c:5155
 copy_process.part.35+0x16f8/0x4b30 kernel/fork.c:1760
 copy_process kernel/fork.c:1615 [inline]
 _do_fork+0x1ef/0xf10 kernel/fork.c:2096
 kernel_thread+0x34/0x40 kernel/fork.c:2155
 call_usermodehelper_exec_sync kernel/umh.c:123 [inline]
 call_usermodehelper_exec_work+0xfe/0x2c0 kernel/umh.c:175
 process_one_work+0xbfd/0x1bc0 kernel/workqueue.c:2113
 worker_thread+0x223/0x1990 kernel/workqueue.c:2247
 kthread+0x37a/0x440 kernel/kthread.c:238
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:517

Freed by task 19280:
 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:3492 [inline]
 kfree+0xca/0x250 mm/slab.c:3807
 lockdep_free_task+0x42/0x4c kernel/locking/lockdep.c:5165
 do_exit+0xd17/0x1ae0 kernel/exit.c:925
 do_group_exit+0x149/0x400 kernel/exit.c:972
 SYSC_exit_group kernel/exit.c:983 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:981
 entry_SYSCALL_64_fastpath+0x1f/0x96

The buggy address belongs to the object at ffff8801cac84e00
 which belongs to the cache kmalloc-8192 of size 8192
The buggy address is located 4248 bytes to the right of
 8192-byte region [ffff8801cac84e00, ffff8801cac86e00)
The buggy address belongs to the page:
page:00000000bc07b851 count:1 mapcount:0 mapping:00000000dd7569ac index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801cac84e00 0000000000000000 0000000100000001
raw: ffffea0007533720 ffffea0007650220 ffff8801db002080 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801cac87d80: fc fc fc fc 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801cac87e00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff8801cac87e80: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
                            ^
 ffff8801cac87f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801cac87f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================