Re: Designated initializers, struct randomization and addressing?

[Kees Cook]

On Tue, Jan 3, 2017 at 3:55 PM, Bruce Korb <bruce.korb@xxxxxxxxx> wrote:
> On Tue, Jan 3, 2017 at 3:47 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>>> how is the code to be verified so that
>>> any use of things like offsetof and any
>>> address/indexing is not impacted?
>
> As a tangential party, I am a bit curious: does the randomization
> plugin result in a compact structure?  I ask because I know many/most
> programmers don't bother with it and so doing so ought to make the
> data more compact.

http://git.kernel.org/cgit/linux/kernel/git/kees/linux.git/tree/scripts/gcc-plugins/randomize_layout_plugin.c?h=kspp/gcc-plugin/randstruct

See full_shuffle() and performance_shuffle(). The latter keeps
variables in the same cacheline. Neither attempt any kind of
compaction.

-Kees

-- 
Kees Cook
Nexus Security