Re: [PATCH 00/10] Misc block layer patches for bcachefs

From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "mingo@kernel.org" <mingo@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"kent.overstreet@gmail.com" <kent.overstreet@gmail.com>,
	"axboe@kernel.dk" <axboe@kernel.dk>
Subject: Re: [PATCH 00/10] Misc block layer patches for bcachefs
Date: Thu, 17 May 2018 20:54:57 +0000	[thread overview]
Message-ID: <a26feed52ec6ed371b3d3b0567e31d1ff4fc31cb.camel@wdc.com> (raw)
In-Reply-To: <20180509013358.16399-1-kent.overstreet@gmail.com>

On Tue, 2018-05-08 at 21:33 -0400, Kent Overstreet wrote:
> [ ... ]

Hello Kent,

With Jens' latest for-next branch I hit the kernel warning shown below. Can
you have a look?

Thanks,

Bart.

==================================================================
BUG: KASAN: use-after-free in bio_advance+0x110/0x1b0
Read of size 4 at addr ffff880156c5e6d0 by task ksoftirqd/10/72

CPU: 10 PID: 72 Comm: ksoftirqd/10 Tainted: G        W         4.17.0-rc4-dbg+ #5
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
Call Trace:
dump_stack+0x9a/0xeb
print_address_description+0x65/0x270
kasan_report+0x232/0x350
bio_advance+0x110/0x1b0
blk_update_request+0x9d/0x5a0
scsi_end_request+0x4c/0x300 [scsi_mod]
scsi_io_completion+0x71e/0xa40 [scsi_mod]
__blk_mq_complete_request+0x143/0x220
srp_recv_done+0x454/0x1100 [ib_srp]
__ib_process_cq+0x9a/0xf0 [ib_core]
ib_poll_handler+0x2d/0x90 [ib_core]
irq_poll_softirq+0xe5/0x1e0
__do_softirq+0x112/0x5f0
run_ksoftirqd+0x29/0x50
smpboot_thread_fn+0x30f/0x410
kthread+0x1b2/0x1d0
ret_from_fork+0x24/0x30

Allocated by task 1356:
kasan_kmalloc+0xa0/0xd0
kmem_cache_alloc+0xed/0x320
mempool_alloc+0xc6/0x210
bio_alloc_bioset+0x128/0x2d0
submit_bh_wbc+0x95/0x2d0
__block_write_full_page+0x2a6/0x5c0
__writepage+0x37/0x80
write_cache_pages+0x305/0x7c0
generic_writepages+0xb9/0x110
do_writepages+0x96/0x180
__filemap_fdatawrite_range+0x162/0x1b0
file_write_and_wait_range+0x4d/0xb0
blkdev_fsync+0x3c/0x70
do_fsync+0x33/0x60
__x64_sys_fsync+0x18/0x20
do_syscall_64+0x6d/0x220
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 72:
__kasan_slab_free+0x130/0x180
kmem_cache_free+0xcd/0x380
blk_update_request+0xc4/0x5a0
blk_update_request+0xc4/0x5a0
scsi_end_request+0x4c/0x300 [scsi_mod]
scsi_io_completion+0x71e/0xa40 [scsi_mod]
__blk_mq_complete_request+0x143/0x220
srp_recv_done+0x454/0x1100 [ib_srp]
__ib_process_cq+0x9a/0xf0 [ib_core]
ib_poll_handler+0x2d/0x90 [ib_core]
irq_poll_softirq+0xe5/0x1e0
__do_softirq+0x112/0x5f0

The buggy address belongs to the object at ffff880156c5e640
which belongs to the cache bio-0 of size 200
The buggy address is located 144 bytes inside of
200-byte region [ffff880156c5e640, ffff880156c5e708)
The buggy address belongs to the page:
page:ffffea00055b1780 count:1 mapcount:0 mapping:0000000000000000 index:0x0 compound_mapcount: 0
ib_srpt:srpt_zerolength_write: ib_srpt 10.196.159.179-24: queued zerolength write
flags: 0x8000000000008100(slab|head)
raw: 8000000000008100 0000000000000000 0000000000000000 0000000100190019
raw: ffffea000543a800 0000000200000002 ffff88015a8f3a00 0000000000000000
ib_srpt:srpt_zerolength_write: ib_srpt 10.196.159.179-22: queued zerolength write
page dumped because: kasan: bad access detected
ib_srpt:srpt_zerolength_write: ib_srpt 10.196.159.179-20: queued zerolength write

Memory state around the buggy address:
ib_srpt:srpt_zerolength_write: ib_srpt 10.196.159.179-18: queued zerolength write
ffff880156c5e580: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
ib_srpt:srpt_zerolength_write_done: ib_srpt 10.196.159.179-24 wc->status 5
ffff880156c5e600: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ib_srpt:srpt_zerolength_write_done: ib_srpt 10.196.159.179-22 wc->status 5
>ffff880156c5e680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ib_srpt:srpt_zerolength_write_done: ib_srpt 10.196.159.179-20 wc->status 5
                                                ^
ffff880156c5e700: fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ib_srpt:srpt_zerolength_write_done: ib_srpt 10.196.159.179-18 wc->status 5
ffff880156c5e780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ib_srpt:srpt_release_channel_work: ib_srpt 10.196.159.179-24
==================================================================

(gdb) list *(bio_advance+0x110)
0xffffffff81450090 is in bio_advance (./include/linux/bvec.h:82).
77                      iter->bi_size = 0;
78                      return false;
79              }
80
81              while (bytes) {
82                      unsigned iter_len = bvec_iter_len(bv, *iter);
83                      unsigned len = min(bytes, iter_len);
84
85                      bytes -= len;
86                      iter->bi_size -= len;