blktrace: Concurrent blktraces are not allowed on loop0
blktrace: Concurrent blktraces are not allowed on loop0
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BUG: KASAN: use-after-free in debugfs_remove fs/debugfs/inode.c:662 [inline]
BUG: KASAN: use-after-free in debugfs_remove+0xef/0x110 fs/debugfs/inode.c:654
Read of size 8 at addr ffff888239646e00 by task syz-executor.3/10953

CPU: 1 PID: 10953 Comm: syz-executor.3 Not tainted 4.14.202-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
 debugfs_remove fs/debugfs/inode.c:662 [inline]
 debugfs_remove+0xef/0x110 fs/debugfs/inode.c:654
 blk_trace_free+0x31/0x130 kernel/trace/blktrace.c:327
 blk_trace_cleanup kernel/trace/blktrace.c:355 [inline]
 __blk_trace_remove+0x68/0xc0 kernel/trace/blktrace.c:368
 blk_trace_ioctl+0x204/0x250 kernel/trace/blktrace.c:770
 blkdev_ioctl+0xec/0x1830 block/ioctl.c:580
 block_ioctl+0xd9/0x120 fs/block_dev.c:1893
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45de59
RSP: 002b:00007fbcc35d3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000009000 RCX: 000000000045de59
RDX: 0000000000000000 RSI: 0000000000001276 RDI: 0000000000000007
RBP: 000000000118bf60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c
R13: 00007ffc3fbed58f R14: 00007fbcc35d49c0 R15: 000000000118bf2c

Allocated by task 10953:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 kmem_cache_alloc+0x124/0x3c0 mm/slab.c:3552
 __d_alloc+0x2a/0xa20 fs/dcache.c:1623
 d_alloc+0x46/0x240 fs/dcache.c:1710
 __lookup_hash fs/namei.c:1571 [inline]
 __lookup_hash+0x101/0x270 fs/namei.c:1563
 lookup_one_len+0x279/0x3a0 fs/namei.c:2539
 start_creating+0xb0/0x200 fs/debugfs/inode.c:314
 __debugfs_create_file+0x4f/0x440 fs/debugfs/inode.c:353
 do_blk_trace_setup+0x36d/0xba0 kernel/trace/blktrace.c:566
 __blk_trace_setup+0xa3/0x120 kernel/trace/blktrace.c:615
 blk_trace_ioctl+0x136/0x250 kernel/trace/blktrace.c:756
 blkdev_ioctl+0xec/0x1830 block/ioctl.c:580
 block_ioctl+0xd9/0x120 fs/block_dev.c:1893
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 4629:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kmem_cache_free+0x7c/0x2b0 mm/slab.c:3758
 __rcu_reclaim kernel/rcu/rcu.h:195 [inline]
 rcu_do_batch kernel/rcu/tree.c:2699 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
 rcu_process_callbacks+0x780/0x1180 kernel/rcu/tree.c:2946
 __do_softirq+0x254/0xa1d kernel/softirq.c:288

The buggy address belongs to the object at ffff888239646dc0
 which belongs to the cache dentry of size 288
The buggy address is located 64 bytes inside of
 288-byte region [ffff888239646dc0, ffff888239646ee0)
The buggy address belongs to the page:
page:ffffea0008e59180 count:1 mapcount:0 mapping:ffff888239646000 index:0x0
flags: 0x57ff00000000100(slab)
raw: 057ff00000000100 ffff888239646000 0000000000000000 000000010000000b
raw: ffffea0008e590a0 ffff88823f8bf448 ffff8880b60b2200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888239646d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888239646d80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff888239646e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888239646e80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888239646f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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