FreeBSD and DEP aka "NX bit"?

[Ivan Voras]

2008/8/24 Matthew Macy <mat.macy at gmail.com>:
> On Sat, Aug 23, 2008 at 5:04 PM, Ivan Voras <ivoras at freebsd.org> wrote:
>> I stumbled upon this Wikipedia page:
>> http://en.wikipedia.org/wiki/Comparison_of_BSD_operating_systems#Security_features
>> and it mentions NX bit is supported in FreeBSD. Is this true? Is it
>> enabled by default?
>
> Yes. However, it is in the upper word so it only works with PAE or
> amd64. "jemalloc" maps the heap NX and thread stacks are mapped NX.
> The default process stack currently needs to be executable because
> sigcode is placed at the start of the stack at the time of process
> creation.

Thanks!

How useful is it without protecting the default stack? IIRC wasn't
stack protection one of the main (marketed) bonuses for NX? (I'm
thinking of the majority of currently popular server software like
apache (preforked) and PostgreSQL...)