From nobody Sun Apr 28 03:54:21 2024 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 (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1520606322138393.36432773983313; Fri, 9 Mar 2018 06:38:42 -0800 (PST) Received: from localhost ([::1]:45639 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1euJAP-0001cN-Dz for importer@patchew.org; Fri, 09 Mar 2018 09:38:41 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33701) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1euJ91-0000nr-BB for qemu-devel@nongnu.org; Fri, 09 Mar 2018 09:37:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1euJ8y-0003HK-6b for qemu-devel@nongnu.org; Fri, 09 Mar 2018 09:37:15 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58858 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 1euJ8y-0003HC-1t for qemu-devel@nongnu.org; Fri, 09 Mar 2018 09:37:12 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 87693406E8A4 for ; Fri, 9 Mar 2018 14:37:07 +0000 (UTC) Received: from sirius.home.kraxel.org (ovpn-116-39.ams2.redhat.com [10.36.116.39]) by smtp.corp.redhat.com (Postfix) with ESMTP id 386A710AF9F2; Fri, 9 Mar 2018 14:37:05 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 7BB7511ABE; Fri, 9 Mar 2018 15:37:04 +0100 (CET) From: Gerd Hoffmann To: qemu-devel@nongnu.org Date: Fri, 9 Mar 2018 15:37:04 +0100 Message-Id: <20180309143704.13420-1-kraxel@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Fri, 09 Mar 2018 14:37:07 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Fri, 09 Mar 2018 14:37:07 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.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] [PATCH v2] vga: fix region calculation 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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Typically the scanline length and the line offset are identical. But in case they are not our calculation for region_end is incorrect. Using line_offset is fine for all scanlines, except the last one where we have to use the actual scanline length. Fixes: CVE-2018-7550 Reported-by: Ross Lagerwall Signed-off-by: Gerd Hoffmann Reviewed-by: Prasad J Pandit Tested-by: Ross Lagerwall --- hw/display/vga.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/hw/display/vga.c b/hw/display/vga.c index 28f298b342..72181330b8 100644 --- a/hw/display/vga.c +++ b/hw/display/vga.c @@ -1483,6 +1483,8 @@ static void vga_draw_graphic(VGACommonState *s, int f= ull_update) =20 region_start =3D (s->start_addr * 4); region_end =3D region_start + (ram_addr_t)s->line_offset * height; + region_end +=3D width * s->get_bpp(s) / 8; /* scanline length */ + region_end -=3D s->line_offset; if (region_end > s->vbe_size) { /* wraps around (can happen with cirrus vbe modes) */ region_start =3D 0; --=20 2.9.3