From patchwork Wed Jun 17 10:46:11 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Petr Matousek X-Patchwork-Id: 485348 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org 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 ozlabs.org (Postfix) with ESMTPS id 586D01401DA for ; Wed, 17 Jun 2015 20:59:24 +1000 (AEST) Received: from localhost ([::1]:45688 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5B3y-0007hY-Td for incoming@patchwork.ozlabs.org; Wed, 17 Jun 2015 06:59:22 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56666) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5ArR-0001Uc-A7 for qemu-devel@nongnu.org; Wed, 17 Jun 2015 06:46:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z5ArI-00078F-JC for qemu-devel@nongnu.org; Wed, 17 Jun 2015 06:46:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40075) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5ArI-000787-Cl; Wed, 17 Jun 2015 06:46:16 -0400 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 331C71BE361; Wed, 17 Jun 2015 10:46:15 +0000 (UTC) Received: from dhcp-25-225.brq.redhat.com (dhcp-1-187.brq.redhat.com [10.34.1.187]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t5HAkB4s032693 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=NO); Wed, 17 Jun 2015 06:46:14 -0400 Date: Wed, 17 Jun 2015 12:46:11 +0200 From: Petr Matousek To: qemu-devel@nongnu.org Message-ID: <20150617104610.GH2422@dhcp-25-225.brq.redhat.com> MIME-Version: 1.0 Content-Disposition: inline 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: matttait@google.com, qemu-stable@nongnu.org, mst@redhat.com Subject: [Qemu-devel] [PATCH] i8254: fix out-of-bounds memory access in pit_ioport_read() 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Due converting PIO to the new memory read/write api we no longer provide separate I/O region lenghts for read and write operations. As a result, reading from PIT Mode/Command register will end with accessing pit->channels with invalid index. Fix this by ignoring read from the Mode/Command register. This is CVE-2015-3214. Signed-off-by: Petr Matousek Reported-by: Matt Tait --- hw/timer/i8254.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/hw/timer/i8254.c b/hw/timer/i8254.c index 3450c98..9b65a33 100644 --- a/hw/timer/i8254.c +++ b/hw/timer/i8254.c @@ -196,6 +196,12 @@ static uint64_t pit_ioport_read(void *opaque, hwaddr addr, PITChannelState *s; addr &= 3; + + if (addr == 3) { + /* Mode/Command register is write only, read is ignored */ + return 0; + } + s = &pit->channels[addr]; if (s->status_latched) { s->status_latched = 0;