linux-kernel - Re: [PATCH v3 3/4] security: DH - remove dead code for zero padding

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Message-ID: <6300797.NZM0BCWY22@tauon.chronox.de>
Date:   Thu, 18 Nov 2021 09:37:01 +0100
From:   Stephan Mueller <smueller@...onox.de>
To:     Mat Martineau <mathew.j.martineau@...ux.intel.com>
Cc:     herbert@...dor.apana.org.au, ebiggers@...nel.org,
        Jarkko Sakkinen <jarkko@...nel.org>,
        "dhowells@...hat.com" <dhowells@...hat.com>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        keyrings <keyrings@...r.kernel.org>, simo@...hat.com
Subject: Re: [PATCH v3 3/4] security: DH - remove dead code for zero padding

Am Mittwoch, 17. November 2021, 22:28:46 CET schrieb Mat Martineau:

Hi Mat,

> On Mon, 15 Nov 2021, Stephan Müller wrote:
> > Remove the specific code that adds a zero padding that was intended
> > to be invoked when the DH operation result was smaller than the
> > modulus. However, this cannot occur any more these days because the
> > function mpi_write_to_sgl is used in the code path that calculates the
> > shared secret in dh_compute_value. This MPI service function guarantees
> > that leading zeros are introduced as needed to ensure the resulting data
> > is exactly as long as the modulus. This implies that the specific code
> > to add zero padding is dead code which can be safely removed.
> > 
> > Signed-off-by: Stephan Mueller <smueller@...onox.de>
> > ---
> > security/keys/dh.c | 25 ++++---------------------
> > 1 file changed, 4 insertions(+), 21 deletions(-)
> 
> Hi Stephan -
> 
> Thanks for the cleanup!

Thank you for the review.
> 
> Acked-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>

I have added your signature to the patch.

Ciao
Stephan