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BUG: KASAN: use-after-free in debugfs_remove+0x10d/0x130 fs/debugfs/inode.c:690
Read of size 8 at addr ffff88805041fe80 by task kworker/0:3/7736

CPU: 0 PID: 7736 Comm: kworker/0:3 Not tainted 5.1.0-rc4-next-20190415 #25
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.cold+0x7c/0x20d mm/kasan/report.c:187
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:316
 kasan_report+0x12/0x20 mm/kasan/common.c:623
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 debugfs_remove+0x10d/0x130 fs/debugfs/inode.c:690
 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:753
 __blk_release_queue+0x1dc/0x3a0 block/blk-sysfs.c:866
 process_one_work+0x98e/0x1790 kernel/workqueue.c:2274
 worker_thread+0x98/0xe40 kernel/workqueue.c:2420
 kthread+0x357/0x430 kernel/kthread.c:254
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 17443:
 save_stack+0x45/0xd0 mm/kasan/common.c:76
 set_track mm/kasan/common.c:88 [inline]
 __kasan_kmalloc mm/kasan/common.c:498 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:471
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:506
 slab_post_alloc_hook mm/slab.h:437 [inline]
 slab_alloc mm/slab.c:3392 [inline]
 kmem_cache_alloc+0x11a/0x6f0 mm/slab.c:3554
 __d_alloc+0x2e/0x8c0 fs/dcache.c:1622
 d_alloc+0x4d/0x280 fs/dcache.c:1701
 d_alloc_parallel+0xf4/0x1bc0 fs/dcache.c:2455
 __lookup_slow+0x1ab/0x500 fs/namei.c:1652
 lookup_one_len+0x16d/0x1a0 fs/namei.c:2541
 start_creating fs/debugfs/inode.c:313 [inline]
 start_creating+0xbf/0x1e0 fs/debugfs/inode.c:289
 __debugfs_create_file+0x65/0x400 fs/debugfs/inode.c:352
 debugfs_create_file+0x5a/0x70 fs/debugfs/inode.c:405
 do_blk_trace_setup+0x376/0xb90 kernel/trace/blktrace.c:528
 __blk_trace_setup+0xe3/0x190 kernel/trace/blktrace.c:577
 blk_trace_ioctl+0x170/0x300 kernel/trace/blktrace.c:716
 blkdev_ioctl+0x276/0x1d10 block/ioctl.c:591
 block_ioctl+0xee/0x130 fs/block_dev.c:1931
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0xd6e/0x1390 fs/ioctl.c:696
 ksys_ioctl+0xab/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+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9:
 save_stack+0x45/0xd0 mm/kasan/common.c:76
 set_track mm/kasan/common.c:88 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:460
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:468
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3764
 __d_free+0x20/0x30 fs/dcache.c:269
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2092 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline]
 rcu_core+0xbac/0x1510 kernel/rcu/tree.c:2291
 __do_softirq+0x266/0x95a kernel/softirq.c:293

The buggy address belongs to the object at ffff88805041fe40
 which belongs to the cache dentry(65:syz1) of size 288
The buggy address is located 64 bytes inside of
 288-byte region [ffff88805041fe40, ffff88805041ff60)
The buggy address belongs to the page:
page:ffffea00014107c0 count:1 mapcount:0 mapping:ffff8880937da780 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0001343dc8 ffffea0001342b88 ffff8880937da780
raw: 0000000000000000 ffff88805041f080 000000010000000b ffff888097ffe240
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888097ffe240

Memory state around the buggy address:
 ffff88805041fd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805041fe00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff88805041fe80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88805041ff00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff88805041ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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