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 26BF4C433F5 for ; Wed, 29 Sep 2021 12:54:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 02B3761214 for ; Wed, 29 Sep 2021 12:54:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343923AbhI2M4c (ORCPT ); Wed, 29 Sep 2021 08:56:32 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:23236 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343889AbhI2M4c (ORCPT ); Wed, 29 Sep 2021 08:56:32 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4HKGXP4W3Jz8tV5; Wed, 29 Sep 2021 20:53:57 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Wed, 29 Sep 2021 20:54:49 +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; Wed, 29 Sep 2021 20:54:49 +0800 Subject: Re: [patch v8 0/7] handle unexpected message from server From: "yukuai (C)" To: , , , CC: , , , References: <20210916093350.1410403-1-yukuai3@huawei.com> Message-ID: <37b222c1-d6b0-3e46-248a-2557db40ae92@huawei.com> Date: Wed, 29 Sep 2021 20:54:48 +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: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.176.73] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) 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 2021/09/23 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(-) >>