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spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34104 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lD3eE-0004BR-LG for qemu-devel@archiver.kernel.org; Fri, 19 Feb 2021 06:08:34 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:40972) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lD3dJ-0003Z5-NL for qemu-devel@nongnu.org; Fri, 19 Feb 2021 06:07:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:55263) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lD3dH-0002IF-DJ for qemu-devel@nongnu.org; Fri, 19 Feb 2021 06:07:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1613732853; h=from:from:reply-to:subject:subject: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=CxMJnJFSyK8tKDZLqe8Dd18Tjid7MzZoGPsGZ4wMoIo=; b=YwfAHmMLI5UCNUV3hhJKcNIVVJy43X8NdZdxCDyy4JJqpVQrU1ASfmCkydD0CqEpQ6FrAR 9VjWRbX50Mhd/MbJjqbZ/VKwh6Yty9SxJcIReKFDxeMg7IdzEAAzbGHm3VoAOzD268vuYY PZ3ktTHJEiuSr8gBkRvQylfIBAgNLRA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-567-cWHCqbCOOICU-8Yt0OxNlQ-1; Fri, 19 Feb 2021 06:07:32 -0500 X-MC-Unique: cWHCqbCOOICU-8Yt0OxNlQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E2C5F100CCC2; Fri, 19 Feb 2021 11:07:30 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-112-191.ams2.redhat.com [10.36.112.191]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3501F702F2; Fri, 19 Feb 2021 11:07:19 +0000 (UTC) Subject: Re: [PATCH v2 0/2] block: Use 'read-zeroes=true' mode by default with 'null-co' driver To: Fam Zheng , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= References: <20210211142656.3818078-1-philmd@redhat.com> <20210213215448.GA67780@ip-172-44-255-31> From: Max Reitz Message-ID: <3da6a2aa-472e-d9e1-b803-303891513274@redhat.com> Date: Fri, 19 Feb 2021 12:07:17 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210213215448.GA67780@ip-172-44-255-31> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , Kevin Wolf , Thomas Huth , qemu-block@nongnu.org, qemu-devel@nongnu.org, Wainer dos Santos Moschetta , Markus Armbruster , Alexander Bulekov , Bandan Das , Stefan Hajnoczi , Cleber Rosa , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 13.02.21 22:54, Fam Zheng wrote: > On 2021-02-11 15:26, Philippe Mathieu-Daudé wrote: >> The null-co driver doesn't zeroize buffer in its default config, >> because it is designed for testing and tests want to run fast. >> However this confuses security researchers (access to uninit >> buffers). > > I'm a little surprised. > > Is changing default the only way to fix this? I'm not opposed to > changing the default but I'm not convinced this is the easiest way. > block/nvme.c also doesn't touch the memory, but defers to the device > DMA, why doesn't that confuse the security checker? > > Cannot we just somehow annotate it in a way that the checker can > understand (akin to how we provide coverity models) and be done? The question is, why wouldn’t we change the default? read-zeroes=true seems the better default to me. I consider silencing valgrind warnings and the like a nice side effect. Max