article on security of various linux

Dave Jones davej at
Fri Sep 10 03:55:36 UTC 2010

On Thu, Sep 09, 2010 at 10:30:57AM -0400, Gregory Maxwell wrote:
 > On Thu, Sep 9, 2010 at 9:45 AM, Neal Becker <ndbecker2 at> wrote:
 > > This article:
 > >
 > >
 > >
 > > seems to say that fedora is ranking poorly in deployment of various
 > > userspace memory protection mechanisms.  Is this information accurate?
 > I asked about one point of this on LWN:
 > Library randomization / prelink
 > Posted Sep 8, 2010 18:26 UTC (Wed) by gmaxwell  (subscriber, #30048) [Link]
 > Anyone know how the library randomization is being counted? 3 bits for
 > fedora doesn't sound right. Is the 3 bits the value for a system vs
 > itself or for this system vs all other systems?
 > "a note here: fedora uses exec-shield which maps libraries in two different
 > regions: ascii-armor (lower 16MB) and the rest. i think what paxtest
 > measured there is the former where the usable entropy is necessarily
 > less than elsewhere and may not be representative of real life apps
 > and their address spaces (not saying the whole ascii-armor region is
 > worth anything for security though ;)"

This article was brought up on fedora-kernel-list last week.

In my tests, I've not been able to reproduce the '3 bits' result.
On current kernels, I see 12 bits for 32-bit, and 'no randomisation' for 64-bit.
I'm not entirely sure yet why we're showing different results on some of the
other tests to other distros too.

I'll poke at it some more tomorrow.


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