Re: [PATCH v2 1/8] wined3d: Set an array of constant buffers as a single CS operation.

[Henri Verbeet]

On Thu, 27 May 2021 at 04:15, Zebediah Figura  wrote:
> +void CDECL wined3d_device_context_set_constant_buffers(struct wined3d_device_context *context,
> -
>    enum wined3d_shader_type type, unsigned int start_idx, unsigned int count,
> -
>    struct wined3d_buffer *const *buffers)
>
> {
>      struct wined3d_state *state = context->state;
> - struct wined3d_buffer *prev;
> - unsigned int i;
> - TRACE("context %p, type %#x, idx %u, buffer %p.\n", context, type, idx, buffer);
> - TRACE("context %p, type %#x, start_idx %u, count %u, buffers %p.\n", context, type, start_idx, count, buffers);
> - if (idx >= MAX_CONSTANT_BUFFERS)
> - if (start_idx + count > MAX_CONSTANT_BUFFERS)
> {
> -
>    WARN("Invalid constant buffer index %u.\n", idx);
> -
>    WARN("Invalid constant buffer index %u, count %u.\n", start_idx, count);
>    return;
> }

"start_idx + count" can overflow. Consider e.g. "start_idx == ~0u,
count = 8;". We typically write such bound checks as "if (start_idx >=
MAX_CONSTANT_BUFFERS || count > MAX_CONSTANT_BUFFERS - start_idx)". We
could conceivably also use something like gcc's
__builtin_uadd_overflow().