audit: type=1400 audit(1598954865.763:8): avc:  denied  { execmem } for  pid=6468 comm="syz-executor908" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
blktrace: Concurrent blktraces are not allowed on loop0
blktrace: Concurrent blktraces are not allowed on loop0
==================================================================
BUG: KASAN: use-after-free in debugfs_remove+0x1c1/0x210 fs/debugfs/inode.c:687
Read of size 8 at addr ffff8880837098c0 by task kworker/0:2/2740

CPU: 0 PID: 2740 Comm: kworker/0:2 Not tainted 4.19.142-syzkaller #0
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+0x1fc/0x2fe lib/dump_stack.c:118
 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1c7 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
 debugfs_remove+0x1c1/0x210 fs/debugfs/inode.c:687
 blk_trace_free+0x31/0x130 kernel/trace/blktrace.c:315
 blk_trace_cleanup kernel/trace/blktrace.c:343 [inline]
 __blk_trace_remove+0x8b/0x100 kernel/trace/blktrace.c:356
 blk_trace_shutdown+0x92/0x100 kernel/trace/blktrace.c:768
 __blk_release_queue+0x235/0x4e0 block/blk-sysfs.c:855
 process_one_work+0x864/0x1570 kernel/workqueue.c:2155
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 6479:
 kmem_cache_alloc+0x122/0x370 mm/slab.c:3559
 __d_alloc+0x2b/0xa10 fs/dcache.c:1610
 d_alloc+0x4a/0x230 fs/dcache.c:1694
 d_alloc_parallel+0xeb/0x19e0 fs/dcache.c:2441
 __lookup_slow+0x18d/0x4a0 fs/namei.c:1655
 lookup_one_len+0x163/0x190 fs/namei.c:2544
 start_creating.part.0+0x62/0x160 fs/tracefs/inode.c:336
 start_creating fs/debugfs/inode.c:301 [inline]
 __debugfs_create_file+0xb8/0x4e0 fs/debugfs/inode.c:352
 do_blk_trace_setup+0x3a5/0xc30 kernel/trace/blktrace.c:542
 __blk_trace_setup+0xca/0x180 kernel/trace/blktrace.c:591
 blk_trace_ioctl+0x155/0x290 kernel/trace/blktrace.c:732
 blkdev_ioctl+0x112/0x1a7e block/ioctl.c:587
 block_ioctl+0xe9/0x130 fs/block_dev.c:1896
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 18:
 __cache_free mm/slab.c:3503 [inline]
 kmem_cache_free+0x7f/0x260 mm/slab.c:3765
 __rcu_reclaim kernel/rcu/rcu.h:236 [inline]
 rcu_do_batch kernel/rcu/tree.c:2584 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2897 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2864 [inline]
 rcu_process_callbacks+0x8ff/0x18b0 kernel/rcu/tree.c:2881
 __do_softirq+0x26c/0x9a0 kernel/softirq.c:292

The buggy address belongs to the object at ffff888083709880
 which belongs to the cache dentry of size 288
The buggy address is located 64 bytes inside of
 288-byte region [ffff888083709880, ffff8880837099a0)
The buggy address belongs to the page:
page:ffffea00020dc240 count:1 mapcount:0 mapping:ffff88821bc44c80 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffffea00020dbbc8 ffffea00020dbc08 ffff88821bc44c80
raw: 0000000000000000 ffff888083709040 000000010000000b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888083709780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888083709800: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff888083709880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888083709900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888083709980: fb fb fb fb fc fc fc fc fc fc fc fc 00 00 00 00
==================================================================