[Spice-devel] [PATCH spice-protocol] stream-device: Specify how padding shoud be inside new structures

[Christophe Fergeau]

On Fri, Feb 23, 2018 at 10:11:46AM +0000, Frediano Ziglio wrote:
> Depending on how structures are initialised in the code is
> possible that implicit padding bytes are not initialised
> causing possible information leaks as the entire structure
> with all padding is sent through device/network.
> 
> Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> ---
>  spice/stream-device.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/spice/stream-device.h b/spice/stream-device.h
> index 2e7c50e..b2f83b5 100644
> --- a/spice/stream-device.h
> +++ b/spice/stream-device.h
> @@ -48,6 +48,8 @@
>   * containing integers up to 64 bit.
>   * All numbers are in little endian format.
>   *
> + * For security reasons structures should not contain implicit paddings.
> + *

Isn't padding inserted by the compiler going to be platform-dependent
anyway? I would say that all structures used in the protocol should be
packed.

Christophe

>   * The protocol can be defined by these states:
>   * - Initial. Device just opened. Guest should wait
>   *   for a message from the host;
> -- 
> 2.14.3
> 
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