Re: revert PIE randomization?

[Kees Cook <kees@outflux.net>]

On Wed, Mar 21, 2007 at 08:01:50PM +0000, Hugh Dickins wrote:
> It was in doing kernel builds that I hit it, nothing special: an
> overnight cycle of kernel building would collapse in a few hours.
> openSUSE 10.2.

I wonder it was the combination of the base addr randomization patch and 
something specific to the openSuSE loader that was sparking the 
failures?  I ran about 22 million execs on Ubuntu Feisty (patched to 
re-include the base addr randomization), with a PIE bash, and never saw 
it.  Hmpf.

> Andi would tell definitively, but I guess it's merely that with so
> much more address space to play with, x86_64 can divide up that space
> more satisfactorily.
> 
> But don't be misled: try "ulimit -s unlimited" and I expect you'll
> find i386 allocating mmap addresses (hence libraries) from the
> opposite end, below ELF_ET_DYN_BASE.

Is there any explicitly documented per-arch "here is the memory layout 
of a process"?  I haven't been able to find anything like this.  I 
suspect it would be a good reference to have; so if no one has any 
hints, I'll try to get something written up.

-- 
Kees Cook                                            @outflux.net