Ndrv setspec() Integer Overflow

The ndrv_setspec Integer Overflow is a vulnerability found in the kernel. i0n1c used this to make the first (publicly released) "untethering" exploit that bypassed Apple's ASLR implementation.

Vulnerability
This exploit was talked about by i0n1c at Blackhat US 2011 in his Exploiting The iOS Kernel presentation starting at slide 41.