RE: [Xen-devel] New heap API and scrubbing

[Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>]

> > Moreover, it appears that there are MANY calls throughout
> > Xen to free_XXXheap_page/s() but I don't see much code
> > that scrubs the pages before freeing them.  Isn't
> > this a potential security issue?  Perhaps it should
> > be easier to free+scrub pages?
> 
> Pages which are currently not scrubbed are either:
>  1. Freed by a domain before it dies, so it has to scrub them.
>  2. Xenheap pages or anonymous domheap pages which thus 
> contained no guest
> data and no security risk in not scrubbing them.

I realize that's true of "data" pages.  I'm no security
expert, but I think I'm referring to "sideband" attacks.
I.e. if an attacker gets enough "non-data" pages (such
as page-table pages) from another domain, there is eventually
sufficient information to derive something useful.
The security guys get into a tizzy about such things.
 
> Feel free to add a free+scrub function.

OK.  Since tmem has true "data" pages to free, I will
do that.

Thanks,
Dan

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel