In article <e814db780812120659qd384182y8f8c1a69d39c2e2e at mail.gmail.com>, Filipe Brandenburger <filbranden at gmail.com> wrote: > Hi, > > We are porting some applications from CentOS 4 to CentOS 5, the > applications use mmap, and we found out that they sometimes crash in > CentOS 5. We found out that this is due to the fact that CentOS 5 does > randomization of the address space when loading binaries, libraries, > and when using mmap, so that is what's causing our problem. > > The thing is, I'm trying to google for it, but I did not find any > useful information on ASLR present in CentOS 5/RHEL 5/Linux 2.6.18. If > anyone has any good pointers on reliable information on what does that > code do, how to configure/tweak it, or how to use mmap properly to > work around the issues, I would really appreciate it. In particular, > if there is a switch/option that would allow us to disable it for some > binaries/libraries only, it would be great, since this could allow us > to do the upgrade sooner and try to find the proper fix for the > problem later. >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 Alternatively, you can run your program with ASLR disabled by using setarch to invoke it: setarch `uname -m` -R yourprog <yourprogoptions> The -R option disables randomisation. You might want to look at the -L option for setarch too (man setarch). Cheers Tony -- Tony Mountifield Work: tony at softins.co.uk - http://www.softins.co.uk Play: tony at mountifield.org - http://tony.mountifield.org