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BUG: KASAN: use-after-free in relay_switch_subbuf+0x8be/0x920 kernel/relay.c:755
Read of size 8 at addr ffff88808abdd058 by task blkid/1750

CPU: 1 PID: 1750 Comm: blkid Not tainted 5.3.0 #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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351
 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482
 kasan_report+0x12/0x17 mm/kasan/common.c:618
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 relay_switch_subbuf+0x8be/0x920 kernel/relay.c:755
 relay_reserve include/linux/relay.h:261 [inline]
 trace_note.isra.0+0x5b8/0x6e0 kernel/trace/blktrace.c:93
 trace_note_tsk kernel/trace/blktrace.c:124 [inline]
 __blk_add_trace+0xb70/0xe10 kernel/trace/blktrace.c:264
 blk_add_trace_plug+0x5d/0x80 kernel/trace/blktrace.c:941
 trace_block_plug include/trace/events/block.h:456 [inline]
 blk_mq_make_request+0x17bc/0x2200 block/blk-mq.c:1988
 generic_make_request block/blk-core.c:1052 [inline]
 generic_make_request+0x23c/0xb50 block/blk-core.c:994
 submit_bio+0x104/0x4d0 block/blk-core.c:1163
 mpage_bio_submit fs/mpage.c:66 [inline]
 mpage_readpages+0x466/0x630 fs/mpage.c:410
 blkdev_readpages+0x2d/0x40 fs/block_dev.c:620
 read_pages+0x108/0x540 mm/readahead.c:126
 __do_page_cache_readahead+0x4e0/0x5d0 mm/readahead.c:212
 ra_submit mm/internal.h:62 [inline]
 ondemand_readahead+0x561/0xd40 mm/readahead.c:492
 page_cache_async_readahead mm/readahead.c:574 [inline]
 page_cache_async_readahead+0x43c/0x7c0 mm/readahead.c:547
 generic_file_buffered_read mm/filemap.c:2079 [inline]
 generic_file_read_iter+0x1239/0x1ce0 mm/filemap.c:2344
 blkdev_read_iter+0x120/0x190 fs/block_dev.c:2007
 call_read_iter include/linux/fs.h:1864 [inline]
 new_sync_read+0x4d7/0x800 fs/read_write.c:414
 __vfs_read+0xe1/0x110 fs/read_write.c:427
 vfs_read+0x1f0/0x440 fs/read_write.c:461
 ksys_read+0x14f/0x290 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x73/0xb0 fs/read_write.c:595
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f0029e47310
Code: 73 01 c3 48 8b 0d 28 4b 2b 00 31 d2 48 29 c2 64 89 11 48 83 c8 ff eb ea 90 90 83 3d e5 a2 2b 00 00 75 10 b8 00 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 6e 8a 01 00 48 89 04 24
RSP: 002b:00007fff8caa3708 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000010000 RCX: 00007f0029e47310
RDX: 0000000000000561 RSI: 0000000001693b48 RDI: 0000000000000003
RBP: 0000000001693b20 R08: 0000000000000018 R09: 0000000001680000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001690030
R13: 0000000000000561 R14: 0000000001690080 R15: 0000000001693b38

Allocated by task 759:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:493 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:466
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:501
 slab_post_alloc_hook mm/slab.h:520 [inline]
 slab_alloc mm/slab.c:3319 [inline]
 kmem_cache_alloc+0x121/0x710 mm/slab.c:3483
 __d_alloc+0x2e/0x8c0 fs/dcache.c:1688
 d_alloc_pseudo+0x1e/0x70 fs/dcache.c:1817
 alloc_file_pseudo+0xe2/0x280 fs/file_table.c:225
 sock_alloc_file+0x50/0x180 net/socket.c:397
 sock_map_fd net/socket.c:420 [inline]
 __sys_socket+0x150/0x220 net/socket.c:1515
 __do_sys_socket net/socket.c:1520 [inline]
 __se_sys_socket net/socket.c:1518 [inline]
 __x64_sys_socket+0x73/0xb0 net/socket.c:1518
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 750:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:455
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:463
 __cache_free mm/slab.c:3425 [inline]
 kmem_cache_free+0x86/0x320 mm/slab.c:3693
 __d_free fs/dcache.c:271 [inline]
 dentry_free+0xe9/0x160 fs/dcache.c:348
 __dentry_kill+0x457/0x600 fs/dcache.c:593
 dentry_kill fs/dcache.c:686 [inline]
 dput+0x819/0xde0 fs/dcache.c:859
 __fput+0x424/0x890 fs/file_table.c:293
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x5a9/0x6a0 arch/x86/entry/common.c:299
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88808abdd000
 which belongs to the cache dentry(81:syz3) of size 288
The buggy address is located 88 bytes inside of
 288-byte region [ffff88808abdd000, ffff88808abdd120)
The buggy address belongs to the page:
page:ffffea00022af740 refcount:1 mapcount:0 mapping:ffff8880a8e76000 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0002540948 ffffea000254a9c8 ffff8880a8e76000
raw: 0000000000000000 ffff88808abdd000 000000010000000b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808abdcf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88808abdcf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88808abdd000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff88808abdd080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808abdd100: fb fb fb fb fc fc fc fc fc fc fc fc 00 00 00 00
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