==================================================================
BUG: KASAN: use-after-free in disk_unblock_events+0x55/0x60 block/genhd.c:1543
Read of size 8 at addr ffff8801d5d0c0e8 by task syz-executor.0/2119

CPU: 1 PID: 2119 Comm: syz-executor.0 Not tainted 4.4.174+ #17
 0000000000000000 a7796e0425d1db0e ffff8801c17b76c0 ffffffff81aad1a1
 0000000000000000 ffffea0007574200 ffff8801d5d0c0e8 0000000000000008
 0000000000000000 ffff8801c17b76f8 ffffffff81490120 0000000000000000
Call Trace:
 [<ffffffff81aad1a1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81aad1a1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff81490120>] print_address_description+0x6f/0x21b mm/kasan/report.c:252
 [<ffffffff81490358>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff81490358>] kasan_report mm/kasan/report.c:408 [inline]
 [<ffffffff81490358>] kasan_report.cold+0x8c/0x2be mm/kasan/report.c:393
 [<ffffffff81484ed4>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 [<ffffffff81a82965>] disk_unblock_events+0x55/0x60 block/genhd.c:1543
 [<ffffffff8154efcc>] __blkdev_get+0x70c/0xdf0 fs/block_dev.c:1297
 [<ffffffff81551938>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1353
 [<ffffffff8155219a>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1508
 [<ffffffff8149154f>] do_dentry_open+0x38f/0xbd0 fs/open.c:749
 [<ffffffff81494d3b>] vfs_open+0x10b/0x210 fs/open.c:862
 [<ffffffff814c5ddf>] do_last fs/namei.c:3269 [inline]
 [<ffffffff814c5ddf>] path_openat+0x136f/0x4470 fs/namei.c:3406
 [<ffffffff814ccab1>] do_filp_open+0x1a1/0x270 fs/namei.c:3440
 [<ffffffff81495668>] do_sys_open+0x2f8/0x600 fs/open.c:1038
 [<ffffffff81599c4a>] C_SYSC_open fs/compat.c:1092 [inline]
 [<ffffffff81599c4a>] compat_SyS_open+0x2a/0x40 fs/compat.c:1090
 [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
 [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
 [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a

Allocated by task 10508:
 [<ffffffff8102e3c6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff81483f22>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff81483f22>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff81483f22>] kasan_kmalloc.part.0+0x62/0xf0 mm/kasan/kasan.c:616
 [<ffffffff81484197>] kasan_kmalloc+0xb7/0xd0 mm/kasan/kasan.c:601
 [<ffffffff814801a3>] kmem_cache_alloc_trace+0x123/0x2d0 mm/slub.c:2642
 [<ffffffff81a81b50>] kmem_cache_alloc_node_trace include/linux/slab.h:367 [inline]
 [<ffffffff81a81b50>] kmalloc_node include/linux/slab.h:514 [inline]
 [<ffffffff81a81b50>] kzalloc_node include/linux/slab.h:631 [inline]
 [<ffffffff81a81b50>] alloc_disk_node+0x50/0x3c0 block/genhd.c:1282
 [<ffffffff81a81edb>] alloc_disk+0x1b/0x20 block/genhd.c:1274
 [<ffffffff81d436d0>] loop_add+0x380/0x830 drivers/block/loop.c:1857
 [<ffffffff81d440a8>] loop_control_ioctl+0x138/0x2f0 drivers/block/loop.c:1988
 [<ffffffff8159b2c3>] C_SYSC_ioctl fs/compat_ioctl.c:1592 [inline]
 [<ffffffff8159b2c3>] compat_SyS_ioctl+0x403/0x2210 fs/compat_ioctl.c:1544
 [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
 [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
 [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a

Freed by task 2119:
 [<ffffffff8102e3c6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff81484820>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff81484820>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff81484820>] kasan_slab_free+0xb0/0x190 mm/kasan/kasan.c:589
 [<ffffffff81481c44>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff81481c44>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff81481c44>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff81481c44>] kfree+0xf4/0x310 mm/slub.c:3749
 [<ffffffff81a80375>] disk_release+0x255/0x330 block/genhd.c:1118
 [<ffffffff81cf785d>] device_release+0x7d/0x220 drivers/base/core.c:247
 [<ffffffff81ab309c>] kobject_cleanup lib/kobject.c:643 [inline]
 [<ffffffff81ab309c>] kobject_release lib/kobject.c:672 [inline]
 [<ffffffff81ab309c>] kref_sub include/linux/kref.h:73 [inline]
 [<ffffffff81ab309c>] kref_put include/linux/kref.h:98 [inline]
 [<ffffffff81ab309c>] kobject_put+0x14c/0x260 lib/kobject.c:689
 [<ffffffff81a7e013>] put_disk+0x23/0x30 block/genhd.c:1346
 [<ffffffff8154ef2c>] __blkdev_get+0x66c/0xdf0 fs/block_dev.c:1290
 [<ffffffff81551938>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1353
 [<ffffffff8155219a>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1508
 [<ffffffff8149154f>] do_dentry_open+0x38f/0xbd0 fs/open.c:749
 [<ffffffff81494d3b>] vfs_open+0x10b/0x210 fs/open.c:862
 [<ffffffff814c5ddf>] do_last fs/namei.c:3269 [inline]
 [<ffffffff814c5ddf>] path_openat+0x136f/0x4470 fs/namei.c:3406
 [<ffffffff814ccab1>] do_filp_open+0x1a1/0x270 fs/namei.c:3440
 [<ffffffff81495668>] do_sys_open+0x2f8/0x600 fs/open.c:1038
 [<ffffffff81599c4a>] C_SYSC_open fs/compat.c:1092 [inline]
 [<ffffffff81599c4a>] compat_SyS_open+0x2a/0x40 fs/compat.c:1090
 [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
 [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
 [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a

The buggy address belongs to the object at ffff8801d5d0bb80
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 1384 bytes inside of
 2048-byte region [ffff8801d5d0bb80, ffff8801d5d0c380)
The buggy address belongs to the page:
BUG: unable to handle kernel paging request at fffffffe31a06840
IP: [<ffffffff811f471e>] cpuacct_charge+0x14e/0x360 kernel/sched/cpuacct.c:247
PGD 2e0d067 PUD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 27 Comm: kworker/0:1 Not tainted 4.4.174+ #17
Workqueue: events vmstat_shepherd
task: ffff8801d9ac8000 task.stack: ffff8801d9ad0000
RIP: 0010:[<ffffffff811f471e>]  [<ffffffff811f471e>] cpuacct_charge+0x14e/0x360 kernel/sched/cpuacct.c:247
RSP: 0000:ffff8801d9ad77a8  EFLAGS: 00010046
RAX: 1ffffffff05d2a33 RBX: 00000000000181a8 RCX: fffffffe31a06840
RDX: fffffbffc6340d08 RSI: ffffffff81b0abec RDI: ffffffff82e95198
RBP: ffff8801d9ad77e8 R08: 0000000000000006 R09: ffff8801d9ac89d8
R10: ffffffff82836880 R11: 0000000000000000 R12: ffffffff82e950c0
R13: dffffc0000000000 R14: 000000005b65c0bc R15: ffffffffd5d0c380
FS:  0000000000000000(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffe31a06840 CR3: 00000001d2ea5000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff811f4630 0000000000000046 0000000000000003 ffff8801d87fc7a0
 ffff8801d87fc740 000000005b65c0bc ffff8801d87fc7f0 0000000000000000
 ffff8801d9ad7830 ffffffff8117c4a3 ffffffff83a7f5d0 ffff8801d9ac88c8
Call Trace:
 [<ffffffff8117c4a3>] update_curr+0x2c3/0x6e0 kernel/sched/fair.c:882
 [<ffffffff8119dedf>] enqueue_entity kernel/sched/fair.c:3512 [inline]
 [<ffffffff8119dedf>] enqueue_task_fair+0x10f/0xb6c0 kernel/sched/fair.c:4711
 [<ffffffff811638e4>] enqueue_task kernel/sched/core.c:858 [inline]
 [<ffffffff811638e4>] activate_task+0x154/0x280 kernel/sched/core.c:874
 [<ffffffff81164b5e>] ttwu_activate kernel/sched/core.c:1736 [inline]
 [<ffffffff81164b5e>] ttwu_do_activate.constprop.0+0xbe/0x1e0 kernel/sched/core.c:1789
 [<ffffffff81168041>] ttwu_queue kernel/sched/core.c:1934 [inline]
 [<ffffffff81168041>] try_to_wake_up+0x6d1/0x1110 kernel/sched/core.c:2068
 [<ffffffff81168bc5>] wake_up_process+0x15/0x20 kernel/sched/core.c:2142
 [<ffffffff8111e40e>] wake_up_worker kernel/workqueue.c:846 [inline]
 [<ffffffff8111e40e>] insert_work+0x21e/0x320 kernel/workqueue.c:1318
 [<ffffffff81120033>] __queue_work+0x3e3/0xec0 kernel/workqueue.c:1433
 [<ffffffff81125db8>] __queue_delayed_work+0x248/0x3b0 kernel/workqueue.c:1495
 [<ffffffff81125f79>] queue_delayed_work_on+0x59/0xb0 kernel/workqueue.c:1533
 [<ffffffff8140c3dd>] vmstat_shepherd+0x16d/0x230 mm/vmstat.c:1490
 [<ffffffff81122c25>] process_one_work+0x825/0x1720 kernel/workqueue.c:2064
 [<ffffffff81124004>] worker_thread+0x4e4/0xf50 kernel/workqueue.c:2196
 [<ffffffff811342c3>] kthread+0x273/0x310 kernel/kthread.c:211
 [<ffffffff82718fc5>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537
Code: 49 8d bc 24 d8 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 ba 01 00 00 49 8b 9c 24 d8 00 00 00 80 3a 00 0f 85 8c 01 00 00 <4a> 03 1c fd 40 4c 1a 83 48 89 d8 48 c1 e8 03 42 80 3c 28 00 0f 
RIP  [<ffffffff811f471e>] cpuacct_charge+0x14e/0x360 kernel/sched/cpuacct.c:247
 RSP <ffff8801d9ad77a8>
CR2: fffffffe31a06840
---[ end trace c31a43a27fbb6d24 ]---