Re: [PATCH] random: add and use memzero_explicit() for clearing data

["Theodore Ts'o" <tytso@mit.edu>]

On Tue, Aug 26, 2014 at 01:11:30AM +0200, Hannes Frederic Sowa wrote:
> On Mo, 2014-08-25 at 22:01 +0200, Daniel Borkmann wrote:
> > zatimend has reported that in his environment (3.16/gcc4.8.3/corei7)
> > memset() calls which clear out sensitive data in extract_{buf,entropy,
> > entropy_user}() in random driver are being optimized away by gcc.
> > 
> > Add a helper memzero_explicit() (similarly as explicit_bzero() variants)
> > that can be used in such cases where a variable with sensitive data is
> > being cleared out in the end. Other use cases might also be in crypto
> > code. [ I have put this into lib/string.c though, as it's always built-in
> > and doesn't need any dependencies then. ]
> > 
> > Fixes kernel bugzilla: 82041
> > 
> > Reported-by: zatimend@hotmail.co.uk
> > Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
> > Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
> > Cc: Alexey Dobriyan <adobriyan@gmail.com>
> 
> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>

Applied to the random tree, thanks.

					- Ted