Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date: Fri, 8 Oct 2021 03:10:26 +0300
From: Konstantin Belousov <>
Cc: David Holland <>
Subject: Re: freezero() and freezeroall()

On Thu, Oct 07, 2021 at 05:00:43PM -0700, Keith Packard wrote:
> Hrm. If this page has ever been written to swap, it sure would be nice
> to be able to erase that copy as well, otherwise there's a persisted
> version of the data which survives power off.
For instance we (FreeBSD) have no way to track all possible locations in
a swap where the page was written sometime in the past.  I doubt that other
operating systems can do that.

Or during physical memory defragmentation, the page might have been
copied and replaced by another physical page.

Also imagine a VM running under hypervisor, and hypervisor deciding to page
out some VM memory.  We have no way to indicate a desire to treat this
specific page as sensitive, to it.

Overall, I think it is only feasible to clear _the page_ itself, without
even trying to provide a kind of guarantee that its data is completely
vanished from the whole system.

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.