On Fri, Jun 27, 2014 at 08:02:48PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <[email protected]>
>
> 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 [email protected]'s rework of what I originally posted)
>
> Signed-off-by: Dr. David Alan Gilbert <[email protected]>
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
