From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59790) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X1FKj-0005HC-0c for qemu-devel@nongnu.org; Sun, 29 Jun 2014 09:39:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X1FKX-0007r8-PL for qemu-devel@nongnu.org; Sun, 29 Jun 2014 09:39:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47591) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X1FKX-0007qs-FM for qemu-devel@nongnu.org; Sun, 29 Jun 2014 09:39:41 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s5TDde1f030476 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Sun, 29 Jun 2014 09:39:40 -0400 Date: Sun, 29 Jun 2014 16:40:05 +0300 From: "Michael S. Tsirkin" Message-ID: <20140629134005.GA26654@redhat.com> References: <1403895768-20496-1-git-send-email-dgilbert@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1403895768-20496-1-git-send-email-dgilbert@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2] [PATCH] Allow mismatched virtio config-len List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert (git)" Cc: pbonzini@redhat.com, qemu-devel@nongnu.org, quintela@redhat.com On Fri, Jun 27, 2014 at 08:02:48PM +0100, Dr. David Alan Gilbert (git) wrote: > 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 Applied, thanks! > --- > 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); > > -- > 1.9.3