From patchwork Wed Feb 10 16:17:39 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 8273191 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 6CAEB9F3CD for ; Wed, 10 Feb 2016 16:18:06 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D8795201C8 for ; Wed, 10 Feb 2016 16:18:05 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id ED93A201CD for ; Wed, 10 Feb 2016 16:18:03 +0000 (UTC) Received: from localhost ([::1]:40648 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aTXSt-0003Sd-9z for patchwork-qemu-devel@patchwork.kernel.org; Wed, 10 Feb 2016 11:18:03 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48544) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aTXSb-0003PG-OR for qemu-devel@nongnu.org; Wed, 10 Feb 2016 11:17:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aTXSY-00084S-H5 for qemu-devel@nongnu.org; Wed, 10 Feb 2016 11:17:45 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36605) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aTXSY-00084M-Bl for qemu-devel@nongnu.org; Wed, 10 Feb 2016 11:17:42 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 9F5955A44 for ; Wed, 10 Feb 2016 16:17:41 +0000 (UTC) Received: from donizetti.redhat.com (ovpn-112-58.ams2.redhat.com [10.36.112.58]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u1AGHd8l017734; Wed, 10 Feb 2016 11:17:40 -0500 From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Wed, 10 Feb 2016 17:17:39 +0100 Message-Id: <1455121059-18280-1-git-send-email-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: lersek@redhat.com, Gerd Hoffmann Subject: [Qemu-devel] [PATCH v2] cirrus_vga: fix off-by-one in blit_region_is_unsafe X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The "max" value is being compared with >=, but addr + width points to the first byte that will _not_ be copied. Laszlo suggested using a "greater than" comparison, instead of subtracting one like it is already done above for the height, so that max remains always positive. The mistake is "safe"---it will reject some blits, but will never cause out-of-bounds writes. Cc: Gerd Hoffmann Signed-off-by: Paolo Bonzini Reviewed-by: Laszlo Ersek --- hw/display/cirrus_vga.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c index b6ce1c8..57b91a7 100644 --- a/hw/display/cirrus_vga.c +++ b/hw/display/cirrus_vga.c @@ -276,14 +276,14 @@ static bool blit_region_is_unsafe(struct CirrusVGAState *s, + ((int64_t)s->cirrus_blt_height-1) * pitch; int32_t max = addr + s->cirrus_blt_width; - if (min < 0 || max >= s->vga.vram_size) { + if (min < 0 || max > s->vga.vram_size) { return true; } } else { int64_t max = addr + ((int64_t)s->cirrus_blt_height-1) * pitch + s->cirrus_blt_width; - if (max >= s->vga.vram_size) { + if (max > s->vga.vram_size) { return true; } }