Kernel Hardening - security-misc

[raja]

Automate mmap randomisation to fix ppc64el

Courtesy of JeremyRand, there appears to be an issue on ppc64el systems when using fixed vm.mmap_rnd_bits and vm.mmap_rnd_compat: A solution is proposed in this PR: It works normally on x64, however, I do not have access to ppc64el or x86 machines to test compatibility. Overall, besides the inclusion of very minor additional comments, I think this is a good idea. Thoughts?