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Date:   Thu, 21 Mar 2019 19:19:18 +0800
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     Vitaly Chikunov <vt@altlinux.org>
Cc:     David Howells <dhowells@redhat.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        linux-integrity@vger.kernel.org, keyrings@vger.kernel.org,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 02/11] crypto: akcipher - check the presence of
 callback before the call
Message-ID: <20190321111918.4kr7vdgz23xzjwed@gondor.apana.org.au>
References: <20190301175918.29694-1-vt@altlinux.org>
 <20190301175918.29694-3-vt@altlinux.org>
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On Fri, Mar 01, 2019 at 08:59:09PM +0300, Vitaly Chikunov wrote:
> Because with introduction of EC-RDSA and change in workings of RSA in
> regard to sign/verify, akcipher could have not all callbacks defined,
> check the presence of callbacks before calling them to increase
> robustness.
> 
> Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
> ---
>  include/crypto/akcipher.h | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/include/crypto/akcipher.h b/include/crypto/akcipher.h
> index 2d690494568c..f537fad1989f 100644
> --- a/include/crypto/akcipher.h
> +++ b/include/crypto/akcipher.h
> @@ -268,7 +268,10 @@ static inline unsigned int crypto_akcipher_maxsize(struct crypto_akcipher *tfm)
>  {
>  	struct akcipher_alg *alg = crypto_akcipher_alg(tfm);
>  
> -	return alg->max_size(tfm);
> +	if (alg->max_size)
> +		return alg->max_size(tfm);
> +	else
> +		return 0;
>  }

Please do these checks at registration time instead and provide
default implementations as needed.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt