Re: [PATCH 20/26] drm/vmwgfx: use array_size

Julia Lawall
2023-06-27T17:33:34Z

On Fri, 23 Jun 2023, Julia Lawall wrote:

> Use array_size to protect against multiplication overflows.
>
> The changes were done using the following Coccinelle semantic patch:
>
> // <smpl>
> @@
> size_t e1,e2;
> expression COUNT;
> identifier alloc = {vmalloc,vzalloc,kvmalloc,kvzalloc};
> @@
>
> (
> alloc(
> - (e1) * (e2)
> + array_size(e1, e2)
> ,...)
> |
> alloc(
> - (e1) * (COUNT)
> + array_size(COUNT, e1)
> ,...)
> )
> // </smpl>
>
> Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
>
> ---
> drivers/gpu/drm/vmwgfx/vmwgfx_devcaps.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_devcaps.c b/drivers/gpu/drm/vmwgfx/vmwgfx_devcaps.c
> index 829df395c2ed..c72fc8111a11 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_devcaps.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_devcaps.c
> @@ -88,7 +88,7 @@ int vmw_devcaps_create(struct vmw_private *vmw)
> uint32_t i;
>
> if (gb_objects) {
> - vmw->devcaps = vzalloc(sizeof(uint32_t) * SVGA3D_DEVCAP_MAX);
> + vmw->devcaps = vzalloc(array_size(SVGA3D_DEVCAP_MAX, sizeof(uint32_t)));
> if (!vmw->devcaps)
> return -ENOMEM;
> for (i = 0; i < SVGA3D_DEVCAP_MAX; ++i) {

Hello,

I think this patch can be dropped, since it's a multiplication of two
constants and no overflow should be possible.

julia