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 X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38A72C433E0 for ; Fri, 5 Mar 2021 14:56:22 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D5F9D65090 for ; Fri, 5 Mar 2021 14:56:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D5F9D65090 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.93811.177169 (Exim 4.92) (envelope-from ) id 1lIBsD-0001TA-Am; Fri, 05 Mar 2021 14:56:13 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 93811.177169; Fri, 05 Mar 2021 14:56:13 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lIBsD-0001T3-75; Fri, 05 Mar 2021 14:56:13 +0000 Received: by outflank-mailman (input) for mailman id 93811; Fri, 05 Mar 2021 14:56:12 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lIBsC-0001S1-Kw for xen-devel@lists.xenproject.org; Fri, 05 Mar 2021 14:56:12 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 2d4b5170-67d1-42ab-9799-0ee723e3293e; Fri, 05 Mar 2021 14:56:11 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B28DEAE89; Fri, 5 Mar 2021 14:56:10 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 2d4b5170-67d1-42ab-9799-0ee723e3293e X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1614956170; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=EsmfXO2Opci0SDdeA3H78wsnKr507wkVL8Sq52e5JX4=; b=ZILXrTu12w4mLs+wvaFiaLk8QhOLmPfn6E4sq4hjojMik5rUSC00Gs7otibqnfghIG2k80 7WtMgOD5id4jjWArW0gdRpjbU+zTDtxbVBTVLZpEWfUg3rZuldSc+PO/ZXl+MWeZDVA1Tu pxDTolU5QhnV6l9STqljaSHJF4yyrFQ= Subject: Re: [PATCH for-4.15] tools/xenstored: liveupdate: Increase the maximum number of parameters To: Ian Jackson Cc: Julien Grall , xen-devel@lists.xenproject.org, raphning@amazon.co.uk, Julien Grall References: <20210305121029.7047-1-julien@xen.org> <24642.12417.651929.972294@mariner.uk.xensource.com> <24642.16967.563767.105312@mariner.uk.xensource.com> <817a49d7-5f11-e53f-5bf5-55d22b157bec@suse.com> <24642.17467.425438.233285@mariner.uk.xensource.com> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <15dde93e-5121-bc13-f931-38c2269a9271@suse.com> Date: Fri, 5 Mar 2021 15:56:10 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <24642.17467.425438.233285@mariner.uk.xensource.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="704O8yJh8rHZpGTF2vPlcr7NyTUAQbm2c" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --704O8yJh8rHZpGTF2vPlcr7NyTUAQbm2c Content-Type: multipart/mixed; boundary="9sOmaYRQCh84d0NzIPpia1XqKmHJwUykI"; protected-headers="v1" From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= To: Ian Jackson Cc: Julien Grall , xen-devel@lists.xenproject.org, raphning@amazon.co.uk, Julien Grall Message-ID: <15dde93e-5121-bc13-f931-38c2269a9271@suse.com> Subject: Re: [PATCH for-4.15] tools/xenstored: liveupdate: Increase the maximum number of parameters References: <20210305121029.7047-1-julien@xen.org> <24642.12417.651929.972294@mariner.uk.xensource.com> <24642.16967.563767.105312@mariner.uk.xensource.com> <817a49d7-5f11-e53f-5bf5-55d22b157bec@suse.com> <24642.17467.425438.233285@mariner.uk.xensource.com> In-Reply-To: <24642.17467.425438.233285@mariner.uk.xensource.com> --9sOmaYRQCh84d0NzIPpia1XqKmHJwUykI Content-Type: multipart/mixed; boundary="------------B0CD4AE6E2177962E1CFA04C" Content-Language: en-US This is a multi-part message in MIME format. --------------B0CD4AE6E2177962E1CFA04C Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 05.03.21 15:46, Ian Jackson wrote: > J=C3=BCrgen Gro=C3=9F writes ("Re: [PATCH for-4.15] tools/xenstored: li= veupdate: Increase the maximum number of parameters"): >> On 05.03.21 15:37, Ian Jackson wrote: >>> J=C3=BCrgen Gro=C3=9F writes ("Re: [PATCH for-4.15] tools/xenstored: = liveupdate: Increase the maximum number of parameters"): >>>> This is the max number of 0 delimited string parameters. Especially = the >>>> stubdom case needs a binary blob (with length, of course) as paramet= er, >>>> and the number of 0 bytes in this data is just limited by the allowe= d >>>> payload length. >>>> >>>> See the comment in line 111 of xenstored_control.c. >>> >>> AFAICT this "live-update" command is variadic. So why is this >>> parameter set here it all then ? >> >> In order to avoid allocating an array for 4000 arguments when there >> are only 5 which need to be treated as strings. >=20 > So this parameter is doing two jobs: 1. enabling non-variadic commands > to take binary input; 2. preventing variadic commands from allocating > unbounded memory. >=20 > The problem with this is that in case 1 exceeding the value is normal > and the final argument is binary data; whereas in case 2 glomming > together the arguments together with zeroes is wrong and potentially > hazrdous. >=20 > I suggest we solve problem 2 by imposing a higher fixed (for all > commands, variadic or not) limit (20 or something) which causes errors > when exceeded, rather than silent argument misinterpretation. Patches welcome. 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