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: Wed, 29 Sep 2021 20:54:48 +0800 [thread overview]
Message-ID: <37b222c1-d6b0-3e46-248a-2557db40ae92@huawei.com> (raw)
In-Reply-To: <f56cc608-ac55-0eee-f3d0-19ba1a8c22ef@huawei.com>
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 ...
>
> 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:[~2021-09-29 12:54 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) [this message]
2021-10-08 7:17 ` yukuai (C)
2021-10-15 8:19 ` yukuai (C)
2021-10-15 16:08 ` Josef Bacik
2021-10-17 13:09 ` Jens Axboe
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