Earlier this year I worked on an exploit for an interesting use-after-free vulnerability in win32k.sys (CVE-2015-0057) and was able to develop a reliable exploit on both 32-bit and 64-bit, affecting XP through Windows 8.1 (with a few exceptions). This writeup describes in detail how I approached exploitation on both architectures, which ended up being somewhat different. I also describe how exploitation works on Windows 8.1 with SMEP and in a low integrity environment.
The post is quite long, but I try to provide a lot of detail to demonstrate what is involved in exploiting this bug instead of glazing over details, although I do still glaze over some. Hopefully the level of detail is helpful.