KASAN: use-after-free Read in blkdev_direct_IO

From: syzbot
Date: Fri Aug 02 2019 - 12:45:09 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 1e78030e Merge tag 'mmc-v5.3-rc1' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=172e72dc600000
kernel config: https://syzkaller.appspot.com/x/.config?x=4c7b914a2680c9c6
dashboard link: https://syzkaller.appspot.com/bug?extid=0a0e5f37746013dc7476
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11fa7830600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12f31c8a600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+0a0e5f37746013dc7476@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in __blkdev_direct_IO fs/block_dev.c:468 [inline]
BUG: KASAN: use-after-free in blkdev_direct_IO+0x13cd/0x1590 fs/block_dev.c:518
Read of size 4 at addr ffff8880a3115f28 by task syz-executor964/10331

CPU: 0 PID: 10331 Comm: syz-executor964 Not tainted 5.3.0-rc2+ #112
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:612
__asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
__blkdev_direct_IO fs/block_dev.c:468 [inline]
blkdev_direct_IO+0x13cd/0x1590 fs/block_dev.c:518
generic_file_direct_write+0x20a/0x4a0 mm/filemap.c:3230
__generic_file_write_iter+0x2ee/0x630 mm/filemap.c:3413
blkdev_write_iter fs/block_dev.c:1993 [inline]
blkdev_write_iter+0x23a/0x440 fs/block_dev.c:1970
call_write_iter include/linux/fs.h:1870 [inline]
new_sync_write+0x4d3/0x770 fs/read_write.c:483
__vfs_write+0xe1/0x110 fs/read_write.c:496
vfs_write+0x268/0x5d0 fs/read_write.c:558
ksys_write+0x14f/0x290 fs/read_write.c:611
__do_sys_write fs/read_write.c:623 [inline]
__se_sys_write fs/read_write.c:620 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:620
do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x44d8f9
Code: e8 7c e6 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 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 0f 83 3b c9 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f85ed575ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000006e0c98 RCX: 000000000044d8f9
RDX: 0000000052698b21 RSI: 0000000020000000 RDI: 0000000000000006
RBP: 00000000006e0c90 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006e0c9c
R13: 00007ffc4e9d0e7f R14: 00007f85ed5769c0 R15: 0000000000000016

Allocated by task 10331:
save_stack+0x23/0x90 mm/kasan/common.c:69
set_track mm/kasan/common.c:77 [inline]
__kasan_kmalloc mm/kasan/common.c:487 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:460
kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:495
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
mempool_alloc_slab+0x47/0x60 mm/mempool.c:513
mempool_alloc+0x169/0x380 mm/mempool.c:393
bio_alloc_bioset+0x3b9/0x680 block/bio.c:477
bio_alloc include/linux/bio.h:400 [inline]
__blkdev_direct_IO fs/block_dev.c:470 [inline]
blkdev_direct_IO+0x8b0/0x1590 fs/block_dev.c:518
generic_file_direct_write+0x20a/0x4a0 mm/filemap.c:3230
__generic_file_write_iter+0x2ee/0x630 mm/filemap.c:3413
blkdev_write_iter fs/block_dev.c:1993 [inline]
blkdev_write_iter+0x23a/0x440 fs/block_dev.c:1970
call_write_iter include/linux/fs.h:1870 [inline]
new_sync_write+0x4d3/0x770 fs/read_write.c:483
__vfs_write+0xe1/0x110 fs/read_write.c:496
vfs_write+0x268/0x5d0 fs/read_write.c:558
ksys_write+0x14f/0x290 fs/read_write.c:611
__do_sys_write fs/read_write.c:623 [inline]
__se_sys_write fs/read_write.c:620 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:620
do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9:
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:449
kasan_slab_free+0xe/0x10 mm/kasan/common.c:457
__cache_free mm/slab.c:3425 [inline]
kmem_cache_free+0x86/0x320 mm/slab.c:3693
mempool_free_slab+0x1e/0x30 mm/mempool.c:520
mempool_free+0xeb/0x370 mm/mempool.c:502
bio_free+0x267/0x420 block/bio.c:255
bio_put+0xda/0x110 block/bio.c:549
blkdev_bio_end_io+0x338/0x4b0 fs/block_dev.c:333
bio_endio+0x611/0xaf0 block/bio.c:1830
req_bio_endio block/blk-core.c:239 [inline]
blk_update_request+0x32e/0xc10 block/blk-core.c:1424
blk_mq_end_request+0x5b/0x560 block/blk-mq.c:557
blk_flush_complete_seq+0x558/0x1030 block/blk-flush.c:196
flush_end_io+0x3d1/0x6d0 block/blk-flush.c:237
__blk_mq_end_request block/blk-mq.c:548 [inline]
blk_mq_end_request+0x32e/0x560 block/blk-mq.c:559
lo_complete_rq+0x210/0x2e0 drivers/block/loop.c:485
blk_done_softirq+0x2fe/0x4d0 block/blk-softirq.c:37
__do_softirq+0x262/0x98c kernel/softirq.c:292

The buggy address belongs to the object at ffff8880a3115f00
which belongs to the cache bio-0 of size 192
The buggy address is located 40 bytes inside of
192-byte region [ffff8880a3115f00, ffff8880a3115fc0)
The buggy address belongs to the page:
page:ffffea00028c4540 refcount:1 mapcount:0 mapping:ffff88821b2978c0 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0002a16f08 ffff8880a7833a48 ffff88821b2978c0
raw: 0000000000000000 ffff8880a3115000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880a3115e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a3115e80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc

ffff8880a3115f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff8880a3115f80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8880a3116000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

---
This bug is generated by a bot. It may contain errors.
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Next message: Suwan Kim: "Re: [PATCH v2 2/2] usbip: Implement SG support to vhci"
Previous message: Pierre-Louis Bossart: "Re: [RFC PATCH 15/40] soundwire: cadence_master: handle multiple status reports per Slave"
Next in thread: syzbot: "Re: KASAN: use-after-free Read in blkdev_direct_IO"
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