From patchwork Fri Feb 16 11:54:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Gerd Hoffmann X-Patchwork-Id: 874377 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3zjWmL5xTGz9rxj for ; Fri, 16 Feb 2018 22:55:14 +1100 (AEDT) Received: from localhost ([::1]:40501 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1emebg-0001eY-Qo for incoming@patchwork.ozlabs.org; Fri, 16 Feb 2018 06:55:12 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36365) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1emeao-0001dQ-Qr for qemu-devel@nongnu.org; Fri, 16 Feb 2018 06:54:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1emeal-0003fK-IP for qemu-devel@nongnu.org; Fri, 16 Feb 2018 06:54:18 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:33712 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1emeal-0003eN-Co for qemu-devel@nongnu.org; Fri, 16 Feb 2018 06:54:15 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 621244022931 for ; Fri, 16 Feb 2018 11:54:12 +0000 (UTC) Received: from sirius.home.kraxel.org (ovpn-116-147.ams2.redhat.com [10.36.116.147]) by smtp.corp.redhat.com (Postfix) with ESMTP id 289E6213AEE2; Fri, 16 Feb 2018 11:54:12 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id D32914F965; Fri, 16 Feb 2018 12:54:10 +0100 (CET) From: Gerd Hoffmann To: qemu-devel@nongnu.org Date: Fri, 16 Feb 2018 12:54:07 +0100 Message-Id: <20180216115410.27287-7-kraxel@redhat.com> In-Reply-To: <20180216115410.27287-1-kraxel@redhat.com> References: <20180216115410.27287-1-kraxel@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Fri, 16 Feb 2018 11:54:12 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Fri, 16 Feb 2018 11:54:12 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'kraxel@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PULL 6/9] 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: Gerd Hoffmann Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Daniel P. Berrangé 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. Berrangé Reviewed-by: Laszlo Ersek Reviewed-by: Philippe Mathieu-Daudé Message-id: 20180205114938.15784-2-berrange@redhat.com Signed-off-by: Gerd Hoffmann --- ui/vnc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/ui/vnc.c b/ui/vnc.c index e371710f4f..746293ddfa 100644 --- a/ui/vnc.c +++ b/ui/vnc.c @@ -1579,8 +1579,8 @@ 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 != 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);