Re: Security fix for remapping of page 0 (was [PATCH] Change ZERO_SIZE_PTR to point at unmapped space)

Alan Cox
2009-06-03T16:13:19Z

> It defaults to 64kB in at least the x86 defconfig files, but to 0 in the
> Kconfig defaults. Also, for some reason it has a "depends on SECURITY",
> which means that if you just default to the old-style unix security you'll
> lose it.
>
> So there are several ways to disable it by mistake. I don't know what
> distros do.

Fedora at least uses SELinux to manage it. You need some kind of security
policy engine running as a few apps really need to map low space (mostly
for vm86)