Re: memory pages nulling when releasing

On Sun, 18 Jun 2006 12:27:22 +0400
"Nick Borisov" <neiro21@xxxxxxxxx> wrote:

Hello everyone!

Could you tell me if FreeBSD supports memory page nulling when
releasing it to prevent unauthorized access to data left in the page
after it's allocated again.

I'm certainly not as expert in this area, but I thought I'd
offer the following suggestions anyway (I'm assuming you're
coding in C, here):
- You might want to look at _malloc_options /
MALLOC_OPTIONS (for example, '_malloc_options = "J";'), though
this might be an expensive way to achieve the goal. See man 2
free for more information
- You could zero a memory range explicitly before free()ing
it, using bzero(3) or memset(3), for instance, or even just by
assignment in some cases. This has the notable advantage that
you can hand-pick which data you're zeroing based on individual
merit

If it does, what sys calls etc provide that?
IMHO this is an important issue when operating data with different
sensivity levels.

Thanks in advance.

Nick

Hope that helps!
--
Nick Withers
email: nick@xxxxxxxxxxxxxxx
Web: http://www.nickwithers.com
Mobile: +61 414 397 446
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