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BUG: KASAN: use-after-free in debugfs_remove+0x4f/0xf0 fs/debugfs/inode.c:684
Read of size 8 at addr ffff888093892900 by task kworker/1:3/8073

CPU: 1 PID: 8073 Comm: kworker/1:3 Not tainted 5.2.0-rc6+ #11
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+0x1d8/0x2f8 lib/dump_stack.c:113
 print_address_description+0x6d/0x310 mm/kasan/report.c:188
 __kasan_report+0x14b/0x1c0 mm/kasan/report.c:317
 kasan_report+0x26/0x50 mm/kasan/common.c:614
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 debugfs_remove+0x4f/0xf0 fs/debugfs/inode.c:684
 blk_trace_free kernel/trace/blktrace.c:312 [inline]
 blk_trace_cleanup kernel/trace/blktrace.c:339 [inline]
 __blk_trace_remove+0xa5/0x180 kernel/trace/blktrace.c:352
 blk_trace_shutdown+0x20b/0x260 kernel/trace/blktrace.c:753
 __blk_release_queue+0x1b0/0x250 block/blk-sysfs.c:902
 process_one_work+0x814/0x1130 kernel/workqueue.c:2269
 worker_thread+0xc01/0x1640 kernel/workqueue.c:2415
 kthread+0x325/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 8636:
 save_stack mm/kasan/common.c:71 [inline]
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc+0x11c/0x1b0 mm/kasan/common.c:489
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497
 slab_post_alloc_hook mm/slab.h:437 [inline]
 slab_alloc mm/slab.c:3326 [inline]
 kmem_cache_alloc+0x1dd/0x2b0 mm/slab.c:3488
 __d_alloc+0x2d/0x6e0 fs/dcache.c:1622
 d_alloc fs/dcache.c:1701 [inline]
 d_alloc_parallel+0xcc/0x1560 fs/dcache.c:2455
 __lookup_slow+0xfc/0x410 fs/namei.c:1652
 lookup_one_len+0x173/0x2a0 fs/namei.c:2541
 start_creating+0xe3/0x1b0 fs/debugfs/inode.c:307
 __debugfs_create_file+0x75/0x480 fs/debugfs/inode.c:346
 debugfs_create_file+0x4a/0x60 fs/debugfs/inode.c:399
 do_blk_trace_setup+0x422/0xa90 kernel/trace/blktrace.c:528
 __blk_trace_setup kernel/trace/blktrace.c:577 [inline]
 blk_trace_ioctl+0x2e8/0x8a0 kernel/trace/blktrace.c:716
 blkdev_ioctl+0x14c0/0x2c10 block/ioctl.c:592
 block_ioctl+0xbd/0x100 fs/block_dev.c:1930
 do_vfs_ioctl+0x7d4/0x1890 fs/ioctl.c:46
 ksys_ioctl fs/ioctl.c:713 [inline]
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718
 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 16:
 save_stack mm/kasan/common.c:71 [inline]
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x12a/0x1e0 mm/kasan/common.c:451
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
 __cache_free mm/slab.c:3432 [inline]
 kmem_cache_free+0xcb/0x170 mm/slab.c:3698
 __d_free+0x20/0x30 fs/dcache.c:271
 __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+0x8d6/0xf90 kernel/rcu/tree.c:2291
 __do_softirq+0x340/0x7b0 arch/x86/include/asm/paravirt.h:777

The buggy address belongs to the object at ffff8880938928c0
 which belongs to the cache dentry(17:syz0) of size 288
The buggy address is located 64 bytes inside of
 288-byte region [ffff8880938928c0, ffff8880938929e0)
The buggy address belongs to the page:
page:ffffea00024e2480 refcount:1 mapcount:0 mapping:ffff88809a002200 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00024e4808 ffffea00024e27c8 ffff88809a002200
raw: 0000000000000000 ffff888093892080 000000010000000b ffff8880639fe880
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8880639fe880

Memory state around the buggy address:
 ffff888093892800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888093892880: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff888093892900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888093892980: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888093892a00: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb
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