linux-hardening - Re: memset() in crypto code

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Date:   Tue, 16 Nov 2021 08:47:26 +0800
From:   Sandy Harris <sandyinchina@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        linux-hardening@...r.kernel.org
Subject: Re: memset() in crypto code

On Fri, Sep 3, 2021 at 2:15 PM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Fri, Sep 03, 2021 at 09:13:43AM +0800, Sandy Harris wrote:
> > Doing this the crypto directory:
> > grep memset *.c | wc -l
> > I get 137 results.
> >
> > The compiler may optimise memset() away, subverting the intent of
> > these operations. We have memzero_explicit() to avoid that problem.
> >
> > Should most or all those memset() calls be replaced?
>
> The ones that are determined to actually need this, sure, but a simple
> grep like that does not actually show that.  You need to read the code
> itself to determine the need or not, please do so.

Done. Patches to follow. I ended up making about a dozen changes
in eight files. Of course, while I did read the code, I do not know it
deeply so I may have misjudged some.