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=-7.5 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 8306AC433E0 for ; Thu, 14 Jan 2021 17:01:52 +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 38FF523B1C for ; Thu, 14 Jan 2021 17:01:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 38FF523B1C 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.67444.120402 (Exim 4.92) (envelope-from ) id 1l060E-0008Ul-Md; Thu, 14 Jan 2021 17:01:42 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 67444.120402; Thu, 14 Jan 2021 17:01:42 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l060E-0008Ue-JQ; Thu, 14 Jan 2021 17:01:42 +0000 Received: by outflank-mailman (input) for mailman id 67444; Thu, 14 Jan 2021 17:01:42 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l060E-0008UZ-4x for xen-devel@lists.xenproject.org; Thu, 14 Jan 2021 17:01:42 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id c35c7ae9-1076-4610-8518-daa9fa118337; Thu, 14 Jan 2021 17:01:41 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 39E4EABD6; Thu, 14 Jan 2021 17:01:40 +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: c35c7ae9-1076-4610-8518-daa9fa118337 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=1610643700; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=m8OJaOnEP3xCFjsMQdEomEuaij5Ujxi3vBX2hG0bQ8Y=; b=GcoHPBE3UzywzxW0/yoLJ93FwCNdhcpailtXQITYU0S9q0xYyXLvJI2GLSVIKMv9SZQgUl qfUVVdvbeSWtFez1L9cmA+5YEG/qgh7xoQEGNtmDa/dn0vtmvvjr4+3mSvKu/UIC1Ag/py xK1ohWbrqiVUWfBFTeOv/uGnOb3pCMo= Subject: Re: [PATCH] argo: don't leak stack contents when returning ring info To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Cc: "xen-devel@lists.xenproject.org" , Christopher Clark References: <20210114165914.rtnzuf5qolifcxv4@Air-de-Roger> From: Jan Beulich Message-ID: <65e8b764-7ace-9562-89ae-e0259e98835d@suse.com> Date: Thu, 14 Jan 2021 18:01:40 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210114165914.rtnzuf5qolifcxv4@Air-de-Roger> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit On 14.01.2021 17:59, Roger Pau Monné wrote: > On Thu, Jan 14, 2021 at 03:01:06PM +0100, Jan Beulich wrote: >> The max_message_size field of the output gets filled only when the flags >> field is non-zero. Don't copy back uninitialized data to guest context. > > I'm afraid I'm missing something. AFAICT ent gets filled from the > user-space contents of data_ent_hnd that's copied from user-space at > the top of the function, Oh, I managed to overlook this multiple time, so ... > so there's no leak from hypervisor stack in > the return path? ... yes indeed. Withdrawing the patch. Thanks for noticing, Jan