Re: [Qemu-devel] [PATCH for-3.1 v2 2/2] usb-mtp: outlaw slashes in filenames

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 3/12/18 9:59, Gerd Hoffmann wrote:
> Slash is unix directory separator, so they are not allowed in filenames.
> Note this also stops the classic escape via "../".
> 
> Fixes: CVE-2018-16867
> Reported-by: Michael Hanselmann <public@hansmi.ch>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> ---
>  hw/usb/dev-mtp.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c
> index 0f6a9702ef..e340a2c6e3 100644
> --- a/hw/usb/dev-mtp.c
> +++ b/hw/usb/dev-mtp.c
> @@ -1719,6 +1719,12 @@ static void usb_mtp_write_metadata(MTPState *s)
>  
>      filename = utf16_to_str(dataset->length, dataset->filename);
>  
> +    if (strchr(filename, '/')) {
> +        usb_mtp_queue_result(s, PARAMETER_NOT_SUPPORTED, d->trans,
> +                             0, 0, 0, 0);
> +        return;
> +    }
> +
>      o = usb_mtp_object_lookup_name(p, filename, dataset->length);
>      if (o != NULL) {
>          next_handle = o->handle;
>