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BUG: KASAN: use-after-free in d_inode include/linux/dcache.h:516 [inline]
BUG: KASAN: use-after-free in relay_switch_subbuf+0x8cc/0x940 kernel/relay.c:761
Read of size 8 at addr ffff888049d9a778 by task syz-executor.4/8695

CPU: 0 PID: 8695 Comm: syz-executor.4 Not tainted 4.19.211-syzkaller #0
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+0x1fc/0x2ef lib/dump_stack.c:118
 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
 d_inode include/linux/dcache.h:516 [inline]
 relay_switch_subbuf+0x8cc/0x940 kernel/relay.c:761
 relay_reserve include/linux/relay.h:261 [inline]
 trace_note+0x5eb/0x750 kernel/trace/blktrace.c:96
 trace_note_tsk kernel/trace/blktrace.c:127 [inline]
 __blk_add_trace+0xb86/0xe20 kernel/trace/blktrace.c:267
 blk_add_trace_plug+0xfe/0x240 kernel/trace/blktrace.c:1000
 trace_block_plug include/trace/events/block.h:456 [inline]
 blk_mq_make_request+0x14b7/0x1c00 block/blk-mq.c:1902
 generic_make_request+0x613/0xdf0 block/blk-core.c:2467
 submit_bio+0xb1/0x430 block/blk-core.c:2576
 ext4_io_submit+0x181/0x210 fs/ext4/page-io.c:356
 ext4_writepages+0x17bf/0x37f0 fs/ext4/inode.c:2910
 do_writepages+0xe5/0x290 mm/page-writeback.c:2344
 __filemap_fdatawrite_range+0x27d/0x350 mm/filemap.c:446
 filemap_write_and_wait_range mm/filemap.c:679 [inline]
 filemap_write_and_wait_range+0x46/0xd0 mm/filemap.c:673
 generic_file_read_iter+0xdf7/0x2b60 mm/filemap.c:2355
 ext4_file_read_iter+0x17b/0x3a0 fs/ext4/file.c:78
 call_read_iter include/linux/fs.h:1815 [inline]
 generic_file_splice_read+0x44a/0x6d0 fs/splice.c:308
 do_splice_to+0x10e/0x160 fs/splice.c:881
 splice_direct_to_actor+0x2b9/0x8d0 fs/splice.c:959
 do_splice_direct+0x1a7/0x270 fs/splice.c:1068
 do_sendfile+0x550/0xc30 fs/read_write.c:1447
 __do_sys_sendfile64 fs/read_write.c:1508 [inline]
 __se_sys_sendfile64+0x147/0x160 fs/read_write.c:1494
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fd0a2c0d109
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd0a1540168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007fd0a2d20100 RCX: 00007fd0a2c0d109
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007fd0a2c670ad R08: 0000000000000000 R09: 0000000000000000
R10: 000000000001dd00 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff987c514f R14: 00007fd0a1540300 R15: 0000000000022000

Allocated by task 13599:
 kmem_cache_alloc+0x122/0x370 mm/slab.c:3559
 __d_alloc+0x2b/0xa10 fs/dcache.c:1612
 d_alloc+0x4a/0x230 fs/dcache.c:1696
 d_alloc_parallel+0xeb/0x19e0 fs/dcache.c:2443
 __lookup_slow+0x18d/0x4a0 fs/namei.c:1655
 lookup_one_len+0x163/0x190 fs/namei.c:2544
 start_creating+0xc9/0x220 fs/debugfs/inode.c:313
 __debugfs_create_file+0x5e/0x480 fs/debugfs/inode.c:352
 relay_create_buf_file+0xf0/0x170 kernel/relay.c:429
 relay_open_buf.part.0+0x781/0xb80 kernel/relay.c:458
 relay_open_buf kernel/relay.c:450 [inline]
 relay_open kernel/relay.c:605 [inline]
 relay_open+0x537/0x9f0 kernel/relay.c:564
 do_blk_trace_setup+0x4f6/0xb40 kernel/trace/blktrace.c:566
 __blk_trace_setup+0xca/0x180 kernel/trace/blktrace.c:609
 blk_trace_ioctl+0x155/0x290 kernel/trace/blktrace.c:750
 blkdev_ioctl+0x112/0x1a80 block/ioctl.c:587
 block_ioctl+0xe9/0x130 fs/block_dev.c:1906
 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 8123:
 __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+0x265/0x980 kernel/softirq.c:292

The buggy address belongs to the object at ffff888049d9a720
 which belongs to the cache dentry of size 288
The buggy address is located 88 bytes inside of
 288-byte region [ffff888049d9a720, ffff888049d9a840)
The buggy address belongs to the page:
page:ffffea0001276680 count:1 mapcount:0 mapping:ffff88813be45200 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffffea00013adec8 ffffea0002398348 ffff88813be45200
raw: 0000000000000000 ffff888049d9a040 000000010000000b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888049d9a600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888049d9a680: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
>ffff888049d9a700: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff888049d9a780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888049d9a800: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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