[Mesa-dev] [PATCH] svga: fix invalid memory reference in needs_to_create_zero()

[Jose Fonseca]

Looks good.

While we're at it, we could ensure the whole key, including num_textures, gets zeroed. The bulk of Mesa/Gallium code assumes structures are zeroed at initialization, which makes it extremely easy to overlook those few places where that's isn't true.

Jose

----- Original Message -----
> The emit->key.fkey info is only valid if we're generating a fragment
> shader.
> We should not look at it if we're generating a vertex shader.
> 
> When generating a vertex shader, the value of
> emit->key.fkey.num_textures was
> garbage and the loop over num_textures would read invalid data.  At
> best
> this would cause us to emit an unused constant.  At worse, we could
> segfault.
> Just by dumb luck, fkey.num_textures was usually a smallish integer.
> 
> NOTE: This is a candidate for the 8.0 branch.
> ---
>  src/gallium/drivers/svga/svga_tgsi_insn.c |   10 +++++-----
>  1 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/src/gallium/drivers/svga/svga_tgsi_insn.c
> b/src/gallium/drivers/svga/svga_tgsi_insn.c
> index ba10fa7..4770816 100644
> --- a/src/gallium/drivers/svga/svga_tgsi_insn.c
> +++ b/src/gallium/drivers/svga/svga_tgsi_insn.c
> @@ -3126,6 +3126,11 @@ needs_to_create_zero( struct
> svga_shader_emitter *emit )
>               emit->key.fkey.tex[i].swizzle_a > PIPE_SWIZZLE_ALPHA)
>              return TRUE;
>        }
> +
> +      for (i = 0; i < emit->key.fkey.num_textures; i++) {
> +         if (emit->key.fkey.tex[i].compare_mode ==
> PIPE_TEX_COMPARE_R_TO_TEXTURE)
> +            return TRUE;
> +      }
>     }
>  
>     if (emit->unit == PIPE_SHADER_VERTEX) {
> @@ -3150,11 +3155,6 @@ needs_to_create_zero( struct
> svga_shader_emitter *emit )
>         emit->info.opcode_count[TGSI_OPCODE_KILP] >= 1)
>        return TRUE;
>  
> -   for (i = 0; i < emit->key.fkey.num_textures; i++) {
> -      if (emit->key.fkey.tex[i].compare_mode ==
> PIPE_TEX_COMPARE_R_TO_TEXTURE)
> -         return TRUE;
> -   }
> -
>     return FALSE;
>  }
>  
> --
> 1.7.3.4
> 
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