From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BCC82C433F5 for ; Fri, 8 Oct 2021 07:17:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AB7B610CE for ; Fri, 8 Oct 2021 07:17:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230156AbhJHHTX (ORCPT ); Fri, 8 Oct 2021 03:19:23 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:28899 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229693AbhJHHTX (ORCPT ); Fri, 8 Oct 2021 03:19:23 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4HQfXt4Kwvzbn8X; Fri, 8 Oct 2021 15:13:02 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Fri, 8 Oct 2021 15:17:26 +0800 Received: from [10.174.176.73] (10.174.176.73) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Fri, 8 Oct 2021 15:17:25 +0800 Subject: Re: [patch v8 0/7] handle unexpected message from server From: "yukuai (C)" To: , , , CC: , , , References: <20210916093350.1410403-1-yukuai3@huawei.com> <37b222c1-d6b0-3e46-248a-2557db40ae92@huawei.com> Message-ID: <5effbc3a-e2f5-063f-6a20-985016d390c6@huawei.com> Date: Fri, 8 Oct 2021 15:17:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <37b222c1-d6b0-3e46-248a-2557db40ae92@huawei.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.176.73] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 ... >> >> 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(-) >>>