[Mesa-dev] [PATCH 01/20] mesa: In emit_texenv() type mismatch was forced with typecast

[Ian Romanick]

On 05/14/2014 10:55 AM, Juha-Pekka Heikkila wrote:
> Type mismatch caused random memory to be copied when casted
> memory area was smaller than expected type.
> 
> Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
> ---
>  src/mesa/main/ff_fragment_shader.cpp | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/src/mesa/main/ff_fragment_shader.cpp b/src/mesa/main/ff_fragment_shader.cpp
> index 8c36097..2115837 100644
> --- a/src/mesa/main/ff_fragment_shader.cpp
> +++ b/src/mesa/main/ff_fragment_shader.cpp
> @@ -877,14 +877,15 @@ emit_texenv(texenv_fragment_program *p, GLuint unit)
>  	 shift = new(p->mem_ctx) ir_constant((float)(1 << rgb_shift));
>        }
>        else {
> -	 float const_data[4] = {
> -	    float(1 << rgb_shift),
> -	    float(1 << rgb_shift),
> -	    float(1 << rgb_shift),
> -	    float(1 << alpha_shift)
> -	 };
> -	 shift = new(p->mem_ctx) ir_constant(glsl_type::vec4_type,
> -					     (ir_constant_data *)const_data);
> +         ir_constant_data const_data;
> +
> +         const_data.f[0] = float(1 << rgb_shift);
> +         const_data.f[1] = float(1 << rgb_shift);
> +         const_data.f[2] = float(1 << rgb_shift);
> +         const_data.f[3] = float(1 << alpha_shift);
> +
> +         shift = new(p->mem_ctx) ir_constant(glsl_type::vec4_type,
> +                                             &const_data);

After this change, does Valgrind complain about (later) reads of
uninitialized memory?  I think we might want to toss an extra memset in
there just to make Valgrind quiet too.  If Valgrind is already quiet,
this patch is

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

as-is.

>        }
>  
>        return saturate(mul(deref, shift));