[8/9] drm/vmwgfx: Annotate struct vmw_surface_dirty with __counted_by

Commit Message

Kees Cook Sept. 22, 2023, 5:32 p.m. UTC

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct vmw_surface_dirty.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Zack Rusin <[e-mail]>
Cc: VMware Graphics Reviewers <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: [e-mail]
Signed-off-by: Kees Cook <[e-mail]>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Zack Rusin Sept. 22, 2023, 9:50 p.m. UTC | #1

On Fri, 2023-09-22 at 10:32 -0700, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct vmw_surface_dirty.
> 
> [1]
> https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Zack Rusin <[e-mail]>
> Cc: VMware Graphics Reviewers <[e-mail]>
> Cc: David Airlie <[e-mail]>
> Cc: Daniel Vetter <[e-mail]>
> Cc: [e-mail]
> Signed-off-by: Kees Cook <[e-mail]>
> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> index 5db403ee8261..2d1d857f99ae 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> @@ -77,7 +77,7 @@ struct vmw_surface_offset {
>  struct vmw_surface_dirty {
>         struct vmw_surface_cache cache;
>         u32 num_subres;
> -       SVGA3dBox boxes[];
> +       SVGA3dBox boxes[] __counted_by(num_subres);
>  };
>  
>  static void vmw_user_surface_free(struct vmw_resource *res);

Thanks!

Reviewed-by: Zack Rusin <[e-mail]>

Patch

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
index 5db403ee8261..2d1d857f99ae 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -77,7 +77,7 @@  struct vmw_surface_offset {
 struct vmw_surface_dirty {
 	struct vmw_surface_cache cache;
 	u32 num_subres;
-	SVGA3dBox boxes[];
+	SVGA3dBox boxes[] __counted_by(num_subres);
 };
 
 static void vmw_user_surface_free(struct vmw_resource *res);