Developed by Hiroaki Etoh, ProPolice is a GCC extension designed to protect applications from stack-smashing attacks. It does this through a number of operations: local stack variables are reordered to place buffers after pointers, protecting them from corruption in case of a buffer overflow; pointers from function arguments are also placed before local buffers; and a canary value is placed after local buffers which, when the function exits, can sometimes be used to detect buffer overflows. ProPolice chooses whether or not to protect a buffer based on automatic heuristics which judge how vulnerable it is, reducing the performance overhead of the protection. It was integrated in OpenBSD's version GCC in December 2002, and first made available in OpenBSD 3.3; it was applied to the kernel in release 3.4. The extension works on all the CPU architectures supported by OpenBSD and is enabled by default, so any C code compiled will be protected without user intervention.