==================================================================
BUG: KASAN: use-after-free in debugfs_remove+0x10b/0x130 fs/debugfs/inode.c:682
Read of size 8 at addr ffff8881b65f2080 by task kworker/1:0/17

CPU: 1 PID: 17 Comm: kworker/1:0 Not tainted 4.20.0-rc4+ #137
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events __blk_release_queue
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
 debugfs_remove+0x10b/0x130 fs/debugfs/inode.c:682
 blk_trace_free+0x35/0x130 kernel/trace/blktrace.c:312
 blk_trace_cleanup kernel/trace/blktrace.c:339 [inline]
 __blk_trace_remove+0x7a/0xa0 kernel/trace/blktrace.c:352
 blk_trace_shutdown+0x63/0x80 kernel/trace/blktrace.c:752
 __blk_release_queue+0x235/0x510 block/blk-sysfs.c:865
 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 6032:
 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
 __d_alloc+0xc8/0xb90 fs/dcache.c:1599
 d_alloc+0x96/0x380 fs/dcache.c:1678
 d_alloc_parallel+0x15a/0x1f40 fs/dcache.c:2421
 __lookup_slow+0x1e6/0x540 fs/namei.c:1654
 lookup_one_len+0x1d8/0x220 fs/namei.c:2543
 start_creating+0xc6/0x200 fs/debugfs/inode.c:308
 __debugfs_create_file+0x63/0x400 fs/debugfs/inode.c:347
 debugfs_create_file+0x57/0x70 fs/debugfs/inode.c:399
 do_blk_trace_setup+0x45d/0xdb0 kernel/trace/blktrace.c:528
 __blk_trace_setup+0xd5/0x180 kernel/trace/blktrace.c:577
 blk_trace_ioctl+0x17a/0x2f0 kernel/trace/blktrace.c:716
 blkdev_ioctl+0x9e9/0x21b0 block/ioctl.c:591
 block_ioctl+0xee/0x130 fs/block_dev.c:1883
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0x1de/0x1790 fs/ioctl.c:696
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
 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
 __d_free+0x20/0x30 fs/dcache.c:257
 __rcu_reclaim kernel/rcu/rcu.h:240 [inline]
 rcu_do_batch kernel/rcu/tree.c:2437 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2716 [inline]
 rcu_process_callbacks+0x100a/0x1ac0 kernel/rcu/tree.c:2697
 __do_softirq+0x308/0xb7e kernel/softirq.c:292

The buggy address belongs to the object at ffff8881b65f2040
 which belongs to the cache dentry of size 288
The buggy address is located 64 bytes inside of
 288-byte region [ffff8881b65f2040, ffff8881b65f2160)
The buggy address belongs to the page:
page:ffffea0006d97c80 count:1 mapcount:0 mapping:ffff8881da980b00 index:0x0
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 ffffea0006d97c08 ffffea0006d97e48 ffff8881da980b00
raw: 0000000000000000 ffff8881b65f2040 000000010000000b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881b65f1f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881b65f2000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8881b65f2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8881b65f2100: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8881b65f2180: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================