==================================================================
BUG: KASAN: use-after-free in disk_unblock_events+0x55/0x60 block/genhd.c:1543
Read of size 8 at addr ffff8800b31cafe8 by task blkid/2594

CPU: 0 PID: 2594 Comm: blkid Not tainted 4.4.170+ #4
 0000000000000000 66a6659c356ef30b ffff8800b2c87730 ffffffff81aaddc1
 0000000000000000 ffffea0002cc7200 ffff8800b31cafe8 0000000000000008
 0000000000000000 ffff8800b2c87768 ffffffff8148fbed 0000000000000000
Call Trace:
 [<ffffffff81aaddc1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81aaddc1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff8148fbed>] print_address_description+0x6f/0x21b mm/kasan/report.c:252
 [<ffffffff8148fe25>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8148fe25>] kasan_report mm/kasan/report.c:408 [inline]
 [<ffffffff8148fe25>] kasan_report.cold+0x8c/0x2be mm/kasan/report.c:393
 [<ffffffff814849d4>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 [<ffffffff81a83585>] disk_unblock_events+0x55/0x60 block/genhd.c:1543
 [<ffffffff8154e91c>] __blkdev_get+0x70c/0xdf0 fs/block_dev.c:1297
 [<ffffffff81551288>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1353
 [<ffffffff81551aea>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1508
 [<ffffffff8149101f>] do_dentry_open+0x38f/0xbd0 fs/open.c:749
 [<ffffffff8149480b>] vfs_open+0x10b/0x210 fs/open.c:862
 [<ffffffff814c572f>] do_last fs/namei.c:3269 [inline]
 [<ffffffff814c572f>] path_openat+0x136f/0x4470 fs/namei.c:3406
 [<ffffffff814cc401>] do_filp_open+0x1a1/0x270 fs/namei.c:3440
 [<ffffffff81495138>] do_sys_open+0x2f8/0x600 fs/open.c:1038
 [<ffffffff8149546d>] SYSC_open fs/open.c:1056 [inline]
 [<ffffffff8149546d>] SyS_open+0x2d/0x40 fs/open.c:1051
 [<ffffffff82717961>] entry_SYSCALL_64_fastpath+0x1e/0x9a

Allocated by task 2578:
 [<ffffffff8102e3c6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff81483a22>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff81483a22>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff81483a22>] kasan_kmalloc.part.0+0x62/0xf0 mm/kasan/kasan.c:616
 [<ffffffff81483c97>] kasan_kmalloc+0xb7/0xd0 mm/kasan/kasan.c:601
 [<ffffffff8147fca3>] kmem_cache_alloc_trace+0x123/0x2d0 mm/slub.c:2642
 [<ffffffff81a82770>] kmem_cache_alloc_node_trace include/linux/slab.h:367 [inline]
 [<ffffffff81a82770>] kmalloc_node include/linux/slab.h:514 [inline]
 [<ffffffff81a82770>] kzalloc_node include/linux/slab.h:631 [inline]
 [<ffffffff81a82770>] alloc_disk_node+0x50/0x3c0 block/genhd.c:1282
 [<ffffffff81a82afb>] alloc_disk+0x1b/0x20 block/genhd.c:1274
 [<ffffffff81d42d04>] loop_add+0x384/0x7e0 drivers/block/loop.c:1824
 [<ffffffff81d43524>] loop_probe+0x154/0x180 drivers/block/loop.c:1931
 [<ffffffff81d0e831>] kobj_lookup+0x221/0x410 drivers/base/map.c:124
 [<ffffffff81a80a5c>] get_gendisk+0x3c/0x2e0 block/genhd.c:689
 [<ffffffff8154e5ac>] __blkdev_get+0x39c/0xdf0 fs/block_dev.c:1193
 [<ffffffff81551421>] blkdev_get+0x481/0x920 fs/block_dev.c:1353
 [<ffffffff81551aea>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1508
 [<ffffffff8149101f>] do_dentry_open+0x38f/0xbd0 fs/open.c:749
 [<ffffffff8149480b>] vfs_open+0x10b/0x210 fs/open.c:862
 [<ffffffff814c572f>] do_last fs/namei.c:3269 [inline]
 [<ffffffff814c572f>] path_openat+0x136f/0x4470 fs/namei.c:3406
 [<ffffffff814cc401>] do_filp_open+0x1a1/0x270 fs/namei.c:3440
 [<ffffffff81495138>] do_sys_open+0x2f8/0x600 fs/open.c:1038
 [<ffffffff8149546d>] SYSC_open fs/open.c:1056 [inline]
 [<ffffffff8149546d>] SyS_open+0x2d/0x40 fs/open.c:1051
 [<ffffffff82717961>] entry_SYSCALL_64_fastpath+0x1e/0x9a

Freed by task 2594:
 [<ffffffff8102e3c6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff81484320>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff81484320>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff81484320>] kasan_slab_free+0xb0/0x190 mm/kasan/kasan.c:589
 [<ffffffff81481744>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff81481744>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff81481744>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff81481744>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff81a80f95>] disk_release+0x255/0x330 block/genhd.c:1118
 [<ffffffff81cf71cd>] device_release+0x7d/0x220 drivers/base/core.c:247
 [<ffffffff81ab3cbc>] kobject_cleanup lib/kobject.c:643 [inline]
 [<ffffffff81ab3cbc>] kobject_release lib/kobject.c:672 [inline]
 [<ffffffff81ab3cbc>] kref_sub include/linux/kref.h:73 [inline]
 [<ffffffff81ab3cbc>] kref_put include/linux/kref.h:98 [inline]
 [<ffffffff81ab3cbc>] kobject_put+0x14c/0x260 lib/kobject.c:689
 [<ffffffff81a7ec33>] put_disk+0x23/0x30 block/genhd.c:1346
 [<ffffffff8154e87c>] __blkdev_get+0x66c/0xdf0 fs/block_dev.c:1290
 [<ffffffff81551288>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1353
 [<ffffffff81551aea>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1508
 [<ffffffff8149101f>] do_dentry_open+0x38f/0xbd0 fs/open.c:749
 [<ffffffff8149480b>] vfs_open+0x10b/0x210 fs/open.c:862
 [<ffffffff814c572f>] do_last fs/namei.c:3269 [inline]
 [<ffffffff814c572f>] path_openat+0x136f/0x4470 fs/namei.c:3406
 [<ffffffff814cc401>] do_filp_open+0x1a1/0x270 fs/namei.c:3440
 [<ffffffff81495138>] do_sys_open+0x2f8/0x600 fs/open.c:1038
 [<ffffffff8149546d>] SYSC_open fs/open.c:1056 [inline]
 [<ffffffff8149546d>] SyS_open+0x2d/0x40 fs/open.c:1051
 [<ffffffff82717961>] entry_SYSCALL_64_fastpath+0x1e/0x9a

The buggy address belongs to the object at ffff8800b31caa80
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 1384 bytes inside of
 2048-byte region [ffff8800b31caa80, ffff8800b31cb280)
The buggy address belongs to the page:
kasan: CONFIG_KASAN_INLINE enabled
kasan: CONFIG_KASAN_INLINE enabledkasan: GPF could be caused by NULL-ptr deref or user memory access
------------[ cut here ]------------
WARNING: CPU: 1 PID: 2073 at kernel/sched/core.c:7941 __might_sleep+0x138/0x1a0 kernel/sched/core.c:7941()
do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff810de4e5>] do_wait+0x265/0xa00 kernel/exit.c:1503