Interesting, that sounds plausible and reasonable, except that the authors mention the minimum granularity of memory reporting is 128KB blocks. For this attack to work, the response to a keystroke has to reliably allocate more than 128KB every time. The vertex and index buffers for a pair of triangles is less than 100 bytes, right? So if only geometry were allocated, you'd only see measurable allocations every once in a while and not for every keystroke. What else might be getting allocated?