From patchwork Fri Jun 27 19:02:48 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Dr. David Alan Gilbert" X-Patchwork-Id: 365113 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org 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 CC67F1400BB for ; Sat, 28 Jun 2014 05:03:22 +1000 (EST) Received: from localhost ([::1]:51918 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X0bQd-0002gt-Mc for incoming@patchwork.ozlabs.org; Fri, 27 Jun 2014 15:03:19 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:32983) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X0bQJ-0002P6-7x for qemu-devel@nongnu.org; Fri, 27 Jun 2014 15:03:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X0bQD-0004q4-3e for qemu-devel@nongnu.org; Fri, 27 Jun 2014 15:02:59 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52519) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X0bQC-0004pz-Ss for qemu-devel@nongnu.org; Fri, 27 Jun 2014 15:02:53 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s5RJ2pFJ000738 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Fri, 27 Jun 2014 15:02:52 -0400 Received: from dgilbert-t530.home.treblig.org (vpn1-7-230.ams2.redhat.com [10.36.7.230]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s5RJ2nln002565; Fri, 27 Jun 2014 15:02:50 -0400 From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org Date: Fri, 27 Jun 2014 20:02:48 +0100 Message-Id: <1403895768-20496-1-git-send-email-dgilbert@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: pbonzini@redhat.com, quintela@redhat.com, mst@redhat.com Subject: [Qemu-devel] [PATCH v2] [PATCH] Allow mismatched virtio config-len 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 From: "Dr. David Alan Gilbert" Commit 'virtio: validate config_len on load' restricted config_len loaded from the wire to match the config_len that the device had. Unfortunately, there are cases where this isn't true, the one we found it on was the wce addition in virtio-blk. Allow mismatched config-lengths: *) If the version on the wire is shorter then fine *) If the version on the wire is longer, load what we have space for and skip the rest. (This is mst@redhat.com's rework of what I originally posted) Signed-off-by: Dr. David Alan Gilbert --- hw/virtio/virtio.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index a3082d5..c1d538c 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -926,12 +926,18 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f) return -1; } config_len = qemu_get_be32(f); - if (config_len != vdev->config_len) { - error_report("Unexpected config length 0x%x. Expected 0x%zx", - config_len, vdev->config_len); - return -1; + + /* + * There are cases where the incoming config can be bigger or smaller + * than what we have; so load what we have space for, and skip + * any excess that's in the stream. + */ + qemu_get_buffer(f, vdev->config, MIN(config_len, vdev->config_len)); + + while (config_len > vdev->config_len) { + qemu_get_byte(f); + config_len--; } - qemu_get_buffer(f, vdev->config, vdev->config_len); num = qemu_get_be32(f);