From nobody Sat Feb 7 08:43:49 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1517831494501328.0580481380845; Mon, 5 Feb 2018 03:51:34 -0800 (PST) Received: from localhost ([::1]:60797 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eifJ3-000525-5T for importer@patchew.org; Mon, 05 Feb 2018 06:51:29 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54238) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eifHV-000489-0s for qemu-devel@nongnu.org; Mon, 05 Feb 2018 06:49:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eifHQ-0008D8-CM for qemu-devel@nongnu.org; Mon, 05 Feb 2018 06:49:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41188) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eifHQ-0008Ck-7U for qemu-devel@nongnu.org; Mon, 05 Feb 2018 06:49:48 -0500 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 mx1.redhat.com (Postfix) with ESMTPS id 687EE61476 for ; Mon, 5 Feb 2018 11:49:47 +0000 (UTC) Received: from localhost.localdomain.com (unknown [10.42.22.189]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8F1E46A838; Mon, 5 Feb 2018 11:49:46 +0000 (UTC) From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= To: qemu-devel@nongnu.org Date: Mon, 5 Feb 2018 11:49:35 +0000 Message-Id: <20180205114938.15784-2-berrange@redhat.com> In-Reply-To: <20180205114938.15784-1-berrange@redhat.com> References: <20180205114938.15784-1-berrange@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Mon, 05 Feb 2018 11:49:47 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 1/4] ui: avoid risk of 32-bit int overflow in VNC buffer check X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laszlo Ersek , Gerd Hoffmann Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Type: text/plain; charset="utf-8" For very large framebuffers, it is theoretically possible for the result of 'vs->throttle_output_offset * VNC_THROTTLE_OUTPUT_LIMIT_SCALE' to exceed the size of a 32-bit int. For this to happen in practice, the video RAM would have to be set to a large enough value, which is not likely today. None the less we can be paranoid against future growth by using division instead of multiplication when checking the limits. Reported-by: Laszlo Ersek Signed-off-by: Daniel P. Berrang=C3=A9 Reviewed-by: Laszlo Ersek Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- ui/vnc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/ui/vnc.c b/ui/vnc.c index 93731accb6..e14e524764 100644 --- a/ui/vnc.c +++ b/ui/vnc.c @@ -1572,8 +1572,8 @@ void vnc_write(VncState *vs, const void *data, size_t= len) * handshake, or from the job thread's VncState clone */ if (vs->throttle_output_offset !=3D 0 && - vs->output.offset > (vs->throttle_output_offset * - VNC_THROTTLE_OUTPUT_LIMIT_SCALE)) { + (vs->output.offset / VNC_THROTTLE_OUTPUT_LIMIT_SCALE) > + vs->throttle_output_offset) { trace_vnc_client_output_limit(vs, vs->ioc, vs->output.offset, vs->throttle_output_offset); vnc_disconnect_start(vs); --=20 2.14.3