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From: Jamie Landeg-Jones <jamie@dyslexicfish.net>
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Date: Mon, 21 Apr 2014 03:19:04 +0100
To: rwmaillists@googlemail.com, freebsd-security@freebsd.org
Subject: Re: De Raadt + FBSD + OpenSSH + hole?
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RW <rwmaillists@googlemail.com> wrote:

> It can return the physical memory, but there are a couple of caveats.
> Firstly, it can only return whole pages. Secondly, it's not returned
> instantaneously to avoid the overhead of page-faults and zeroing pages
> if that region is remalloced. It's left to the page-daemon to recover
> the physical memory in its own time, and it remains readable by it's
> previous process until it's reassigned.

Again, thanks for clearing that up for me. I wasn't all that far
off-base after all, but yours and Nathans replies make sense!

So there is a real world use for calloc after all! (though only as
a bug catching security measure - no sane program should ever read
its memory it hasn't yet written to!)

cheers, jamie