Stack-Smashing Protector
Formerly known as "ProPolice," the stack-smashing protector is an extension to the GNU Compiler Collection that helps mitigate the damage that can be done by buffer overflow based attacks.
The stack-smashing protector was originally written, and still maintained by Hiroaki Etoh, of IBM.
So far it remains a patch external to GCC, and must be added to GCC by developers wishing to employ stack-smashing protection in their programs. At this time, only a small number of operating system developers utilize the stack-smashing protector in their projects by default; OpenBSD and DragonFly BSD. Gentoo Linux also has a version of their software distribution (Hardened Gentoo) that contains the stack-smashing protector patch, but as Gentoo is primarilly a source based, meta-disribution, this cannot be considdered "out of the box" support.