From: "yukuai (C)" <yukuai3@huawei.com>
To: <josef@toxicpanda.com>, <axboe@kernel.dk>, <ming.lei@redhat.com>,
<hch@infradead.org>
Cc: <linux-block@vger.kernel.org>, <nbd@other.debian.org>,
<linux-kernel@vger.kernel.org>, <yi.zhang@huawei.com>
Subject: Re: [patch v8 0/7] handle unexpected message from server
Date: Fri, 15 Oct 2021 16:19:47 +0800 [thread overview]
Message-ID: <326edfba-01d3-9921-de9a-24134c592012@huawei.com> (raw)
In-Reply-To: <5effbc3a-e2f5-063f-6a20-985016d390c6@huawei.com>
On 2021/10/08 15:17, yukuai (C) wrote:
> On 2021/09/29 20:54, yukuai (C) wrote:
>> On 2021/09/23 21:33, yukuai (C) wrote:
>>> On 2021/09/16 17:33, Yu Kuai wrote:
>>>
>>> Hi, jens
>>>
>>> Any interest to apply this series?
>>
>> friendly ping ...
>
> Hi, Jens
>
> friendly ping again ...
Hi, Jens
friendly ping again ...
>>>
>>> Thanks,
>>> Kuai
>>>> This patch set tries to fix that client might oops if nbd server send
>>>> unexpected message to client, for example, our syzkaller report a uaf
>>>> in nbd_read_stat():
>>>>
>>>> Call trace:
>>>> dump_backtrace+0x0/0x310 arch/arm64/kernel/time.c:78
>>>> show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158
>>>> __dump_stack lib/dump_stack.c:77 [inline]
>>>> dump_stack+0x144/0x1b4 lib/dump_stack.c:118
>>>> print_address_description+0x68/0x2d0 mm/kasan/report.c:253
>>>> kasan_report_error mm/kasan/report.c:351 [inline]
>>>> kasan_report+0x134/0x2f0 mm/kasan/report.c:409
>>>> check_memory_region_inline mm/kasan/kasan.c:260 [inline]
>>>> __asan_load4+0x88/0xb0 mm/kasan/kasan.c:699
>>>> __read_once_size include/linux/compiler.h:193 [inline]
>>>> blk_mq_rq_state block/blk-mq.h:106 [inline]
>>>> blk_mq_request_started+0x24/0x40 block/blk-mq.c:644
>>>> nbd_read_stat drivers/block/nbd.c:670 [inline]
>>>> recv_work+0x1bc/0x890 drivers/block/nbd.c:749
>>>> process_one_work+0x3ec/0x9e0 kernel/workqueue.c:2147
>>>> worker_thread+0x80/0x9d0 kernel/workqueue.c:2302
>>>> kthread+0x1d8/0x1e0 kernel/kthread.c:255
>>>> ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174
>>>>
>>>> 1) At first, a normal io is submitted and completed with scheduler:
>>>>
>>>> internel_tag = blk_mq_get_tag -> get tag from sched_tags
>>>> blk_mq_rq_ctx_init
>>>> sched_tags->rq[internel_tag] = sched_tag->static_rq[internel_tag]
>>>> ...
>>>> blk_mq_get_driver_tag
>>>> __blk_mq_get_driver_tag -> get tag from tags
>>>> tags->rq[tag] = sched_tag->static_rq[internel_tag]
>>>>
>>>> So, both tags->rq[tag] and sched_tags->rq[internel_tag] are pointing
>>>> to the request: sched_tags->static_rq[internal_tag]. Even if the
>>>> io is finished.
>>>>
>>>> 2) nbd server send a reply with random tag directly:
>>>>
>>>> recv_work
>>>> nbd_read_stat
>>>> blk_mq_tag_to_rq(tags, tag)
>>>> rq = tags->rq[tag]
>>>>
>>>> 3) if the sched_tags->static_rq is freed:
>>>>
>>>> blk_mq_sched_free_requests
>>>> blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i)
>>>> -> step 2) access rq before clearing rq mapping
>>>> blk_mq_clear_rq_mapping(set, tags, hctx_idx);
>>>> __free_pages() -> rq is freed here
>>>>
>>>> 4) Then, nbd continue to use the freed request in nbd_read_stat()
>>>>
>>>> Changes in v8:
>>>> - add patch 5 to this series.
>>>> - modify some words.
>>>> Changes in v7:
>>>> - instead of exposing blk_queue_exit(), using percpu_ref_put()
>>>> directly.
>>>> - drop the ref right after nbd_handle_reply().
>>>> Changes in v6:
>>>> - don't set cmd->status to error if request is completed before
>>>> nbd_clear_req().
>>>> - get 'q_usage_counter' to prevent accessing freed request through
>>>> blk_mq_tag_to_rq(), instead of using blk_mq_find_and_get_req().
>>>> Changes in v5:
>>>> - move patch 1 & 2 in v4 (patch 4 & 5 in v5) behind
>>>> - add some comment in patch 5
>>>> Changes in v4:
>>>> - change the name of the patchset, since uaf is not the only problem
>>>> if server send unexpected reply message.
>>>> - instead of adding new interface, use blk_mq_find_and_get_req().
>>>> - add patch 5 to this series
>>>> Changes in v3:
>>>> - v2 can't fix the problem thoroughly, add patch 3-4 to this series.
>>>> - modify descriptions.
>>>> - patch 5 is just a cleanup
>>>> Changes in v2:
>>>> - as Bart suggested, add a new helper function for drivers to get
>>>> request by tag.
>>>>
>>>> Yu Kuai (7):
>>>> nbd: don't handle response without a corresponding request message
>>>> nbd: make sure request completion won't concurrent
>>>> nbd: check sock index in nbd_read_stat()
>>>> nbd: don't start request if nbd_queue_rq() failed
>>>> nbd: clean up return value checking of sock_xmit()
>>>> nbd: partition nbd_read_stat() into nbd_read_reply() and
>>>> nbd_handle_reply()
>>>> nbd: fix uaf in nbd_handle_reply()
>>>>
>>>> drivers/block/nbd.c | 135
>>>> +++++++++++++++++++++++++++++++-------------
>>>> 1 file changed, 96 insertions(+), 39 deletions(-)
>>>>
next prev parent reply other threads:[~2021-10-15 8:20 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-16 9:33 [patch v8 0/7] handle unexpected message from server Yu Kuai
2021-09-16 9:33 ` [patch v8 1/7] nbd: don't handle response without a corresponding request message Yu Kuai
2021-09-16 9:33 ` [patch v8 2/7] nbd: make sure request completion won't concurrent Yu Kuai
2021-09-16 9:33 ` [patch v8 3/7] nbd: check sock index in nbd_read_stat() Yu Kuai
2021-09-19 10:34 ` yukuai (C)
2021-09-22 9:22 ` Ming Lei
2021-09-22 12:12 ` Eric Blake
2021-09-22 12:21 ` yukuai (C)
2021-09-22 15:56 ` Wouter Verhelst
2021-09-23 0:29 ` Ming Lei
2021-09-16 9:33 ` [patch v8 4/7] nbd: don't start request if nbd_queue_rq() failed Yu Kuai
2021-09-16 12:48 ` Ming Lei
2021-09-16 9:33 ` [patch v8 5/7] nbd: clean up return value checking of sock_xmit() Yu Kuai
2021-09-16 12:49 ` Ming Lei
2021-09-16 9:33 ` [patch v8 6/7] nbd: partition nbd_read_stat() into nbd_read_reply() and nbd_handle_reply() Yu Kuai
2021-09-16 12:53 ` Ming Lei
2021-09-16 9:33 ` [patch v8 7/7] nbd: fix uaf in nbd_handle_reply() Yu Kuai
2021-09-16 12:58 ` Ming Lei
2021-09-16 13:10 ` yukuai (C)
2021-09-16 13:55 ` Ming Lei
2021-09-16 14:05 ` yukuai (C)
2021-09-16 14:18 ` [PATCH v9] " Yu Kuai
2021-09-17 3:33 ` Ming Lei
2021-10-17 13:09 ` Jens Axboe
2021-09-23 13:33 ` [patch v8 0/7] handle unexpected message from server yukuai (C)
2021-09-29 12:54 ` yukuai (C)
2021-10-08 7:17 ` yukuai (C)
2021-10-15 8:19 ` yukuai (C) [this message]
2021-10-15 16:08 ` Josef Bacik
2021-10-17 13:09 ` Jens Axboe
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