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BUG: KASAN: use-after-free in iov_iter_revert+0x976/0x9d0 lib/iov_iter.c:890
Read of size 4 at addr ffff88003bb2d888 by task loop6/8723

CPU: 0 PID: 8723 Comm: loop6 Not tainted 4.13.0-rc7-next-20170831+ #12
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x24e/0x340 mm/kasan/report.c:409
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
 iov_iter_revert+0x976/0x9d0 lib/iov_iter.c:890
 generic_file_read_iter+0x1883/0x26c0 mm/filemap.c:2197
 blkdev_read_iter+0x105/0x170 fs/block_dev.c:1918
 call_read_iter include/linux/fs.h:1738 [inline]
 lo_rw_aio+0x9e9/0xc20 drivers/block/loop.c:501
 do_req_filebacked drivers/block/loop.c:539 [inline]
 loop_handle_cmd drivers/block/loop.c:1694 [inline]
 loop_queue_work+0x1f91/0x3900 drivers/block/loop.c:1708
 kthread_worker_fn+0x340/0x9b0 kernel/kthread.c:635
 loop_kthread_worker_fn+0x51/0x60 drivers/block/loop.c:850
 kthread+0x39c/0x470 kernel/kthread.c:231
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

Allocated by task 9998:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3561
 mempool_alloc_slab+0x44/0x60 mm/mempool.c:449
 mempool_alloc+0x16a/0x4b0 mm/mempool.c:329
 bio_alloc_bioset+0x3c7/0x750 block/bio.c:486
 bio_alloc include/linux/bio.h:417 [inline]
 mpage_alloc.isra.6+0x5c/0x260 fs/mpage.c:78
 do_mpage_readpage+0x134a/0x19e0 fs/mpage.c:285
 mpage_readpages+0x626/0x8a0 fs/mpage.c:382
 blkdev_readpages+0x2c/0x40 fs/block_dev.c:589
 read_pages mm/readahead.c:121 [inline]
 __do_page_cache_readahead+0x6c6/0xc00 mm/readahead.c:199
 force_page_cache_readahead+0x1fe/0x340 mm/readahead.c:232
 page_cache_sync_readahead+0xd6/0x100 mm/readahead.c:505
 do_generic_file_read mm/filemap.c:1950 [inline]
 generic_file_read_iter+0x164a/0x26c0 mm/filemap.c:2213
 blkdev_read_iter+0x105/0x170 fs/block_dev.c:1918
 call_read_iter include/linux/fs.h:1738 [inline]
 new_sync_read fs/read_write.c:400 [inline]
 __vfs_read+0x6ad/0xa00 fs/read_write.c:412
 vfs_read+0x124/0x360 fs/read_write.c:433
 SYSC_read fs/read_write.c:549 [inline]
 SyS_read+0xef/0x220 fs/read_write.c:542
 entry_SYSCALL_64_fastpath+0x1f/0xbe

Freed by task 8723:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3503 [inline]
 kmem_cache_free+0x77/0x280 mm/slab.c:3763
 mempool_free_slab+0x1d/0x30 mm/mempool.c:456
 mempool_free+0xd4/0x1d0 mm/mempool.c:438
 bio_free+0x11c/0x190 block/bio.c:265
 bio_put+0x14f/0x180 block/bio.c:558
 mpage_end_io+0x143/0x1b0 fs/mpage.c:57
 bio_endio+0x2f8/0x8d0 block/bio.c:1843
 req_bio_endio block/blk-core.c:204 [inline]
 blk_update_request+0x2a6/0xe20 block/blk-core.c:2738
 blk_mq_end_request+0x54/0x120 block/blk-mq.c:509
 lo_complete_rq+0xbe/0x1f0 drivers/block/loop.c:460
 __blk_mq_complete_request+0x38f/0x6c0 block/blk-mq.c:550
 blk_mq_complete_request+0x4f/0x60 block/blk-mq.c:570
 lo_rw_aio_complete+0x5e/0x80 drivers/block/loop.c:468
 blkdev_bio_end_io+0x22a/0x700 fs/block_dev.c:309
 bio_endio+0x2f8/0x8d0 block/bio.c:1843
 req_bio_endio block/blk-core.c:204 [inline]
 blk_update_request+0x2a6/0xe20 block/blk-core.c:2738
 blk_mq_end_request+0x54/0x120 block/blk-mq.c:509
 lo_complete_rq+0xbe/0x1f0 drivers/block/loop.c:460
 __blk_mq_complete_request_remote+0x58/0x70 block/blk-mq.c:519
 flush_smp_call_function_queue+0x2d6/0x450 kernel/smp.c:247
 generic_smp_call_function_single_interrupt+0x13/0x30 kernel/smp.c:192
 smp_call_function_single_interrupt+0x10f/0x650 arch/x86/kernel/smp.c:295

The buggy address belongs to the object at ffff88003bb2d800
 which belongs to the cache bio-0 of size 192
The buggy address is located 136 bytes inside of
 192-byte region [ffff88003bb2d800, ffff88003bb2d8c0)
The buggy address belongs to the page:
page:ffffea0000eecb40 count:1 mapcount:0 mapping:ffff88003bb2d000 index:0x0
flags: 0x100000000000100(slab)
raw: 0100000000000100 ffff88003bb2d000 0000000000000000 0000000100000010
raw: ffffea0000f105e0 ffffea0000e866e0 ffff88003c414940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88003bb2d780: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88003bb2d800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88003bb2d880: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                      ^
 ffff88003bb2d900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88003bb2d980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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