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BUG: KASAN: use-after-free in debugfs_remove+0x10d/0x130 fs/debugfs/inode.c:684
Read of size 8 at addr ffff888095c6a080 by task syz-executor.4/21778

CPU: 0 PID: 21778 Comm: syz-executor.4 Not tainted 5.2.0-rc5+ #57
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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:188
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 debugfs_remove+0x10d/0x130 fs/debugfs/inode.c:684
 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_ioctl+0x239/0x300 kernel/trace/blktrace.c:731
 blkdev_ioctl+0x126/0x1c10 block/ioctl.c:592
 block_ioctl+0xee/0x130 fs/block_dev.c:1930
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0xd5f/0x1380 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+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4592c9
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f81f8005c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004592c9
RDX: 0000000000000000 RSI: 0000000000001276 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f81f80066d4
R13: 00000000004c0940 R14: 00000000004d34a0 R15: 00000000ffffffff

Allocated by task 21664:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:489 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
 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+0x11a/0x6f0 mm/slab.c:3488
 __d_alloc+0x2e/0x8c0 fs/dcache.c:1622
 d_alloc+0x4d/0x280 fs/dcache.c:1701
 d_alloc_parallel+0xf4/0x1bb0 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:307 [inline]
 start_creating+0xbf/0x1e0 fs/debugfs/inode.c:283
 __debugfs_create_file+0x65/0x3d0 fs/debugfs/inode.c:346
 debugfs_create_file+0x5a/0x70 fs/debugfs/inode.c:399
 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+0x126/0x1c10 block/ioctl.c:592
 block_ioctl+0xee/0x130 fs/block_dev.c:1930
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0xd5f/0x1380 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+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 21661:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x102/0x150 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+0x86/0x260 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+0xba5/0x1500 kernel/rcu/tree.c:2291
 __do_softirq+0x25c/0x94c kernel/softirq.c:292

The buggy address belongs to the object at ffff888095c6a040
 which belongs to the cache dentry(65:syz4) of size 288
The buggy address is located 64 bytes inside of
 288-byte region [ffff888095c6a040, ffff888095c6a160)
The buggy address belongs to the page:
page:ffffea0002571a80 refcount:1 mapcount:0 mapping:ffff88809f62ed80 index:0xffff888095c6a720
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0002472208 ffffea00028bcec8 ffff88809f62ed80
raw: ffff888095c6a720 ffff888095c6a040 0000000100000009 ffff88805e7ce1c0
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88805e7ce1c0

Memory state around the buggy address:
 ffff888095c69f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888095c6a000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff888095c6a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888095c6a100: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888095c6a180: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb
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