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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 9468DC47247 for ; Tue, 5 May 2020 09:20:17 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 5DFCF206B9 for ; Tue, 5 May 2020 09:20:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cdrkYEQO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5DFCF206B9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:48506 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jVtkO-000388-GM for qemu-devel@archiver.kernel.org; Tue, 05 May 2020 05:20:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45600) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jVtjp-0002cH-5p for qemu-devel@nongnu.org; Tue, 05 May 2020 05:19:41 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:25717 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jVtjo-0004fv-HU for qemu-devel@nongnu.org; Tue, 05 May 2020 05:19:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588670379; 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=U4vhjQF4ENmA/SSW0P31nwlQjBbQBmUz5xTfSxmUKKc=; b=cdrkYEQORbtI8ja3FPVQvbaXm81fSjOuyhaGTX6a5omMFR5Cj2mDV+KduIlhJW8LNCeksK oc39HTxbE5q52ZrRTmHonRTaYWBScRG1R+fh8oMtlt20FjdvE/kYz0RjaoMPaT6vZ4ppG0 59FmbvczQk7SS/4Oi6uhhrICgAVMApc= 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-168-MU8S34XjO0mpPn9434En9g-1; Tue, 05 May 2020 05:19:36 -0400 X-MC-Unique: MU8S34XjO0mpPn9434En9g-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3AF081054F92; Tue, 5 May 2020 09:19:35 +0000 (UTC) Received: from linux.fritz.box (ovpn-112-11.ams2.redhat.com [10.36.112.11]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1589D5C1B2; Tue, 5 May 2020 09:19:33 +0000 (UTC) Date: Tue, 5 May 2020 11:19:32 +0200 From: Kevin Wolf To: Alberto Garcia Subject: Re: [PATCH v3] qcow2: Avoid integer wraparound in qcow2_co_truncate() Message-ID: <20200505091927.GF5759@linux.fritz.box> References: <20200504155217.10325-1-berto@igalia.com> <6fefd4af-3687-7f38-3933-aa67f2f221e8@redhat.com> <20200505085412.GD5759@linux.fritz.box> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/05 00:37:40 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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: qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 05.05.2020 um 11:16 hat Alberto Garcia geschrieben: > On Tue 05 May 2020 10:54:12 AM CEST, Kevin Wolf wrote: > > But I think there is a more important problem with the test: It seems > > to pass even with old binaries that don't have the fix. Is this only > > on my system or do you get the same? >=20 > With old binaries when qcow2_cluster_zeroize() is called it receives > bytes =3D (UINT64_MAX - 9216), however that number is then used to > calculate the number of affected clusters, so it's rounded up, wraps > around again and back to zero. There's no visible sign of the error, it > just happens to work fine. >=20 > If there was a raw data file then we would try to write UINT64_MAX-9216 > bytes to it, but in this case there's no backing file allowed and > therefore the image is not zeroed, so qcow2_cluster_zeroize() never > happens. >=20 > Why the test case then? There was a mistake with my first patch and > there it crashed (due to an assertion), that's why Eric thought it would > be a good idea to add a test case anyway, in case we have to change that > code in the future and we screw up. Thanks for the explanation, this makes sense. I'll apply the patch now. Kevin