[CentOS] Information about ASLR (Address Space Layout Randomization) in CentOS 5

Filipe Brandenburger filbranden at gmail.com
Fri Dec 12 16:17:13 UTC 2008


Hi,

On Fri, Dec 12, 2008 at 11:10, Tony Mountifield
<tony at softins.clara.co.uk> wrote:
> From what I've been able to find, you can disable ASLR completely by
> putting the following line in /etc/sysctl.conf:
> kernel.randomize_va_space = 0

Thanks, I had just found that out, we tested it and indeed it works.

> Alternatively, you can run your program with ASLR disabled by using
> setarch to invoke it:
> setarch `uname -m` -R yourprog <yourprogoptions>

I didn't know about this one, sounds good. I'll have a good look at
"man setarch" and also try this out in the next couple of days.

Quick question: from "man setarch", the effect of using -R is "turns
on ADDR_NO_RANDOMIZE". Is it possible to use this flag
ADDR_NO_RANDOMIZE somewhere that will force that binary to use that
option always? I've read something about ELF headers, I wonder if that
is something that could be set there, and if it is, how do I change
the ELF headers to set it?

Thanks!
Filipe


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