[PATCH wayland] scanner: avoid executable stack

[Mart Raudsepp]

Ühel kenal päeval, K, 02.03.2016 kell 11:06, kirjutas Pekka Paalanen:
> From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> 
> Before this patch:
> $ scanelf -lpqe ./wayland-scanner
> RWX --- ---  ./wayland-scanner
> 
> That indicates the stack is executable, which is a bad thing for
> security. Wayland-scanner does not actually need an executable stack,
> it
> is just an oversight from using an .S file in the sources.
> 
> Add a special incantation in dtddata.S to make it not cause the stack
> to
> become executable.
> 
> Reported-by: leio at gentoo.org
> Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>

Confirmed that our QA warning is fixed with this and that basic DTD
validation still works (embedded DTD is readable by wayland-scanner).

Tested-by: Mart Raudsepp <leio at gentoo.org>

> ---
>  src/dtddata.S | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/src/dtddata.S b/src/dtddata.S
> index 68e3435..ce51133 100644
> --- a/src/dtddata.S
> +++ b/src/dtddata.S
> @@ -20,6 +20,14 @@
>   * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
>   */
>  
> +/*
> + * Avoid executable stack.
> + * from: https://wiki.gentoo.org/wiki/Hardened/GNU_stack_quickstart
> + */
> +#if defined(__linux__) && defined(__ELF__)
> +.section .note.GNU-stack,"",%progbits
> +#endif
> +
>  /* from: http://www.linuxjournal.com/content/embedding-file-executab
> le-aka-hello-world-version-5967#comment-348129 */
>  
>  .macro binfile name file