Get the Whitepaper called Kernel Exploitation 6: NULL pointer dereference.
You can download it from the following link: https://packetstormsecurity.com/files/download/145983/6-null-pointer-dereference.pdf
Source: https://packetstormsecurity.com/files/145983/Kernel-Exploitation-Part-6-NULL-Pointer-Dereference.html