Re: [RFC PATCH v4 24/27] mm/mmap: Create a guard area between VMAs

Eugene Syromiatnikov
2018-10-03T21:21:28Z

On Wed, Oct 03, 2018 at 06:52:40PM +0200, Jann Horn wrote:
> On Wed, Oct 3, 2018 at 6:32 PM Eugene Syromiatnikov <esyr@redhat.com> wrote:
> > I'm not sure, however, whether such a change that provides no ability
> > to configure or affect it will go well with all the supported
> > architectures.
>
> Is there a concrete reason why you think an architecture might not
> like this? As far as I can tell, the virtual address space overhead
> should be insignificant even for 32-bit systems.

Not really, and not architectures per se, but judging by some past
experiences with enabling ASLR, I would expect that all kinds of weird
applications may start to behave in all kinds of strange ways.

Not that I have anything more than this doubt, however; but this sort of
change without any ability to tune or revert it still looks unusual to me.