[Mesa-dev] [PATCH] glsl: Fix overflow of ImageAccess[] array.

[Ilia Mirkin]

On Sat, Feb 13, 2016 at 8:27 PM, Kenneth Graunke <kenneth at whitecape.org> wrote:
> The ImageAccess array is statically sized to MAX_IMAGE_UNIFORMS:
>
>    GLenum ImageAccess[MAX_IMAGE_UNIFORMS];
>
> There was no bounds checking ensuring we don't overflow.  Passing in a
> shader with too many uniforms would cause writes to extend into other
> fields, such as sh->NumImages.
>
> Later linker checks already handle reporting an error when there are too
> many images, so just avoid corrupting structures here.
>
> This rearranges the logic a bit to look more like the sampler case.
>
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/compiler/glsl/link_uniforms.cpp | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/src/compiler/glsl/link_uniforms.cpp b/src/compiler/glsl/link_uniforms.cpp
> index 7072c16..f08ca47 100644
> --- a/src/compiler/glsl/link_uniforms.cpp
> +++ b/src/compiler/glsl/link_uniforms.cpp
> @@ -649,15 +649,15 @@ private:
>               current_var->data.image_write_only ? GL_WRITE_ONLY :
>                  GL_READ_WRITE);
>
> -         for (unsigned j = 0; j < MAX2(1, uniform->array_elements); ++j)
> -            prog->_LinkedShaders[shader_type]->
> -               ImageAccess[this->next_image + j] = access;
> +         const unsigned first = this->next_image;
>
>           /* Increment the image index by 1 for non-arrays and by the
>            * number of array elements for arrays.
>            */
>           this->next_image += MAX2(1, uniform->array_elements);
>
> +         for (unsigned i = first; i < MIN2(next_image, MAX_IMAGE_UNIFORMS); i++)

It's a bit odd that you do this->next_image += foo, but then use
next_image directly... if that's the style, I guess it's OK.

> +            prog->_LinkedShaders[shader_type]-> ImageAccess[i] = access;

Remove the space before ImageAccess?

With that,

Reviewed-by: Ilia Mirkin <imirkin at alum.mit.edu>

>        }
>     }
>
> --
> 2.7.1
>
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