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BUG: KASAN: use-after-free in debugfs_remove+0x10d/0x130 fs/debugfs/inode.c:717
Read of size 8 at addr ffff8880936254e0 by task kworker/0:4/8745

CPU: 0 PID: 8745 Comm: kworker/0:4 Not tainted 5.3.0-rc6-next-20190830 #75
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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:634
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 debugfs_remove+0x10d/0x130 fs/debugfs/inode.c:717
 blk_trace_free+0x38/0x140 kernel/trace/blktrace.c:312
 blk_trace_cleanup kernel/trace/blktrace.c:339 [inline]
 __blk_trace_remove+0x78/0xa0 kernel/trace/blktrace.c:352
 blk_trace_shutdown+0x67/0x90 kernel/trace/blktrace.c:747
 __blk_release_queue+0x219/0x380 block/blk-sysfs.c:905
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 8129:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:510 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:518
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc mm/slab.c:3319 [inline]
 kmem_cache_alloc+0x121/0x710 mm/slab.c:3483
 __d_alloc+0x2e/0x8c0 fs/dcache.c:1688
 d_alloc+0x4d/0x280 fs/dcache.c:1767
 __lookup_hash+0xcd/0x190 fs/namei.c:1540
 filename_create+0x1a7/0x4f0 fs/namei.c:3635
 user_path_create fs/namei.c:3692 [inline]
 do_symlinkat+0xf3/0x290 fs/namei.c:4147
 __do_sys_symlink fs/namei.c:4173 [inline]
 __se_sys_symlink fs/namei.c:4171 [inline]
 __x64_sys_symlink+0x59/0x80 fs/namei.c:4171
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8183:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3425 [inline]
 kmem_cache_free+0x86/0x320 mm/slab.c:3693
 __d_free+0x20/0x30 fs/dcache.c:271
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2157 [inline]
 rcu_core+0x581/0x1560 kernel/rcu/tree.c:2377
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2386
 __do_softirq+0x262/0x98c kernel/softirq.c:292

The buggy address belongs to the object at ffff8880936254a0
 which belongs to the cache dentry(65:syz4) of size 288
The buggy address is located 64 bytes inside of
 288-byte region [ffff8880936254a0, ffff8880936255c0)
The buggy address belongs to the page:
page:ffffea00024d8940 refcount:1 mapcount:0 mapping:ffff8880974efc40 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00025151c8 ffffea00016c56c8 ffff8880974efc40
raw: 0000000000000000 ffff888093625080 000000010000000b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888093625380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888093625400: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
>ffff888093625480: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff888093625500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888093625580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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