Some traces in extract_size() should show us what happens... And why it happens only for Maanke.
Actually, it happens not only to him. I guess the reason is hypview build was disabled for a long time, I was sure it works for me too and -- it does not! So Alan, better check by yourself, too :)
Anyway, patch is pretty trivial, see attachment. Since stack size could be also negative, I guess the code was meant as check for upper boundary for negative numbers (as (2^32)/2 - 1 = 0x7fffffff is for positive ones) but for some reason it was done in that strange way.