An address space layout randomization (ASLR) RFC was recently posted on the freebsd-arch mailing list, which is cause for excitement. ASLR is an important technology in system security: the randomization of the arrangement of data in a program’s address space makes it more difficult for memory attacks—such as buffer overflow attacks—to access critical points in memory. Given the wide use of FreeBSD in many critical applications this is a good thing.

The RFC itself is also worth reading, as it covers the history, development, and implementation details of a specific deployment of ASLR. Implementing ASLR is no easy feat—requiring detailed coordination between the operating system kernel and specialized executables—so one can learn a lot from reading the developers’ in-depth summary of their work.