KASAN: use-after-free Read in __blkdev_direct_IO

From: syzbot
Date: Thu Aug 08 2019 - 12:48:08 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 629f8205 Merge tag 'for-linus-20190730' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13e50eb4600000
kernel config: https://syzkaller.appspot.com/x/.config?x=e397351d2615e10
dashboard link: https://syzkaller.appspot.com/bug?extid=a1fc36a4d12501564d34
compiler: clang version 9.0.0 (/home/glider/llvm/clang 80fee25776c2fb61e74c1ecb1a523375c2500b69)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a1fc36a4d12501564d34@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in __blkdev_direct_IO+0xb3d/0x1310 fs/block_dev.c:468
Read of size 4 at addr ffff888037bc2028 by task syz-executor.0/5655

CPU: 0 PID: 5655 Comm: syz-executor.0 Not tainted 5.3.0-rc2+ #56
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+0x1d8/0x2f8 lib/dump_stack.c:113
print_address_description+0x75/0x5b0 mm/kasan/report.c:351
__kasan_report+0x14b/0x1c0 mm/kasan/report.c:482
kasan_report+0x26/0x50 mm/kasan/common.c:612
__asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
__blkdev_direct_IO+0xb3d/0x1310 fs/block_dev.c:468
blkdev_direct_IO+0xbe/0xd0 fs/block_dev.c:518
generic_file_direct_write+0x22e/0x440 mm/filemap.c:3230
__generic_file_write_iter+0x2af/0x520 mm/filemap.c:3413
blkdev_write_iter+0x2f2/0x420 fs/block_dev.c:1993
? 0xffffffff81000000
call_write_iter include/linux/fs.h:1870 [inline]
new_sync_write fs/read_write.c:483 [inline]
__vfs_write+0x617/0x7d0 fs/read_write.c:496
vfs_write+0x275/0x590 fs/read_write.c:558
ksys_write+0x16b/0x2a0 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+0x7b/0x90 fs/read_write.c:620
do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459829
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f56f3b24c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459829
RDX: 0000000052698b21 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f56f3b256d4
R13: 00000000004c5db7 R14: 00000000004e00e0 R15: 00000000ffffffff

Allocated by task 5655:
save_stack mm/kasan/common.c:69 [inline]
set_track mm/kasan/common.c:77 [inline]
__kasan_kmalloc+0x11c/0x1b0 mm/kasan/common.c:487
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+0x1f5/0x2e0 mm/slab.c:3483
mempool_alloc_slab+0x4d/0x70 mm/mempool.c:513
mempool_alloc+0x15f/0x6c0 mm/mempool.c:393
bio_alloc_bioset+0x210/0x670 block/bio.c:477
bio_alloc include/linux/bio.h:400 [inline]
__blkdev_direct_IO+0xa29/0x1310 fs/block_dev.c:470
blkdev_direct_IO+0xbe/0xd0 fs/block_dev.c:518
generic_file_direct_write+0x22e/0x440 mm/filemap.c:3230
__generic_file_write_iter+0x2af/0x520 mm/filemap.c:3413
blkdev_write_iter+0x2f2/0x420 fs/block_dev.c:1993
call_write_iter include/linux/fs.h:1870 [inline]
new_sync_write fs/read_write.c:483 [inline]
__vfs_write+0x617/0x7d0 fs/read_write.c:496
vfs_write+0x275/0x590 fs/read_write.c:558
ksys_write+0x16b/0x2a0 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+0x7b/0x90 fs/read_write.c:620
do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9:
save_stack mm/kasan/common.c:69 [inline]
set_track mm/kasan/common.c:77 [inline]
__kasan_slab_free+0x12a/0x1e0 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+0x81/0xf0 mm/slab.c:3693
mempool_free_slab+0x1d/0x30 mm/mempool.c:520
mempool_free+0xd5/0x350 mm/mempool.c:502
bio_put+0x35a/0x420 block/bio.c:253
blkdev_bio_end_io+0x336/0x430 fs/block_dev.c:333
bio_endio+0x4ff/0x570 block/bio.c:1830
req_bio_endio block/blk-core.c:239 [inline]
blk_update_request+0x385/0xf80 block/blk-core.c:1424
blk_mq_end_request+0x42/0x80 block/blk-mq.c:557
blk_flush_complete_seq+0x5e1/0xd10 block/blk-flush.c:196
flush_end_io+0x4d2/0x670 block/blk-flush.c:237
__blk_mq_end_request+0x38a/0x410 block/blk-mq.c:548
blk_mq_end_request+0x55/0x80 block/blk-mq.c:559
lo_complete_rq+0x13b/0x270 drivers/block/loop.c:485
blk_done_softirq+0x362/0x3e0 block/blk-softirq.c:37
__do_softirq+0x333/0x7c4 arch/x86/include/asm/paravirt.h:778

The buggy address belongs to the object at ffff888037bc2000
which belongs to the cache bio-0 of size 192
The buggy address is located 40 bytes inside of
192-byte region [ffff888037bc2000, ffff888037bc20c0)
The buggy address belongs to the page:
page:ffffea0000def080 refcount:1 mapcount:0 mapping:ffff88821ac91540 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000167a2c8 ffffea0001e21ac8 ffff88821ac91540
raw: 0000000000000000 ffff888037bc2000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888037bc1f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888037bc1f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

ffff888037bc2000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff888037bc2080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff888037bc2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Next message: Joe Perches: "Re: [PATCH] isdn: hysdn: Fix error spaces around '*'"
Previous message: Rafael J. Wysocki: "Re: [PATCH V4 2/2] cpufreq: intel_pstate: Implement QoS supported freq constraints"
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