Does ASLR mean rebasing dlls isn't required?

Question

Am I right in thinking there is no point in rebasing our dlls during our build if we use ASLR as the dlls will be rebased again anyway when the kernel comes to load them?

I am concerned that our application is often used on Terminal Services machines. So, if rebasing occurs at load time, we could end up with dlls being rebased for each process they are loaded into (there would be one process per session). And this would result in more memory usage and paging than we want to pay for. Do I need to be concerned?

I've found the following blog post that says the rebasing only happens once and it is system wide: Matt Evans - Enabling ASLR for memory savings?. I haven't seen any other references about this, so just wanted to be sure if I use ASLR and don't rebase during our build I won't cause memory problems on a Terminal Services box?

Answer 1

So based on my reading you should not have a problem. ASLR causes the the dll's to be loaded to semi random memory address and should not just start rebasing for every process. If you want to check memory use of dll's there is a free tool called MassiveRebase that lets you dynamically load two dll's and view info about their memory use. The was designed to view changes that aslr may have on memory. The tool and more about it can be found here: http://www.tmurgent.com/appv/index.php/en/resources/tools/137-massive-rebase

Hope this helps.