From nobody Fri Apr 19 17:42:47 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.zoho.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; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1487682228972532.4116230038317; Tue, 21 Feb 2017 05:03:48 -0800 (PST) Received: from localhost ([::1]:44405 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cgA6b-0008PN-QT for importer@patchew.org; Tue, 21 Feb 2017 08:03:45 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45492) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cg9RW-0003SY-O8 for qemu-devel@nongnu.org; Tue, 21 Feb 2017 07:21:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cg9RS-0004qV-OV for qemu-devel@nongnu.org; Tue, 21 Feb 2017 07:21:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47462) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cg9RS-0004pT-IU for qemu-devel@nongnu.org; Tue, 21 Feb 2017 07:21:14 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4B1F642BBA for ; Tue, 21 Feb 2017 12:21:14 +0000 (UTC) Received: from nilsson.home.kraxel.org (ovpn-116-47.ams2.redhat.com [10.36.116.47]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v1LCLDnY003385; Tue, 21 Feb 2017 07:21:13 -0500 Received: by nilsson.home.kraxel.org (Postfix, from userid 500) id 5E2AC80874; Tue, 21 Feb 2017 13:21:11 +0100 (CET) From: Gerd Hoffmann To: qemu-devel@nongnu.org Date: Tue, 21 Feb 2017 13:21:03 +0100 Message-Id: <1487679663-3264-1-git-send-email-kraxel@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 21 Feb 2017 12:21:14 +0000 (UTC) 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] cirrus: add blit_is_unsafe call to cirrus_bitblt_cputovideo (CVE-2017-2620) 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" CIRRUS_BLTMODE_MEMSYSSRC blits do NOT check blit destination and blit width, at all. Oops. Fix it. Security impact: high. The missing blit destination check allows to write to host memory. Basically same as CVE-2014-8106 for the other blit variants. Signed-off-by: Gerd Hoffmann --- hw/display/cirrus_vga.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c index 1deb520..b9e7cb1 100644 --- a/hw/display/cirrus_vga.c +++ b/hw/display/cirrus_vga.c @@ -900,6 +900,10 @@ static int cirrus_bitblt_cputovideo(CirrusVGAState * s) { int w; =20 + if (blit_is_unsafe(s, true)) { + return 0; + } + s->cirrus_blt_mode &=3D ~CIRRUS_BLTMODE_MEMSYSSRC; s->cirrus_srcptr =3D &s->cirrus_bltbuf[0]; s->cirrus_srcptr_end =3D &s->cirrus_bltbuf[0]; @@ -925,6 +929,10 @@ static int cirrus_bitblt_cputovideo(CirrusVGAState * s) } s->cirrus_srccounter =3D s->cirrus_blt_srcpitch * s->cirrus_blt_he= ight; } + + /* the blit_is_unsafe call above should catch this */ + assert(s->cirrus_blt_srcpitch <=3D CIRRUS_BLTBUFSIZE); + s->cirrus_srcptr =3D s->cirrus_bltbuf; s->cirrus_srcptr_end =3D s->cirrus_bltbuf + s->cirrus_blt_srcpitch; cirrus_update_memory_access(s); --=20 1.8.3.1