linux-kernel - Re: [PATCH v6 04/11] crypto: qce: skcipher: Return unsupported if any three keys are same for DES3 algorithms

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Date:   Wed, 10 Feb 2021 18:18:53 +1100
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     davem@...emloft.net, bjorn.andersson@...aro.org,
        ebiggers@...gle.com, ardb@...nel.org, sivaprak@...eaurora.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 04/11] crypto: qce: skcipher: Return unsupported if
 any three keys are same for DES3 algorithms

On Sun, Feb 07, 2021 at 09:39:39AM -0500, Thara Gopinath wrote:
>
> +	/*
> +	 * The crypto engine does not support any two keys
> +	 * being the same for triple des algorithms. The
> +	 * verify_skcipher_des3_key does not check for all the
> +	 * below conditions. Return -ENOKEY in case any two keys
> +	 * are the same. Revisit to see if a fallback cipher
> +	 * is needed to handle this condition.
> +	 */
> +	memcpy(_key, key, DES3_EDE_KEY_SIZE);
> +	if (!((_key[0] ^ _key[2]) | (_key[1] ^ _key[3])) |
> +	    !((_key[2] ^ _key[4]) | (_key[3] ^ _key[5])) |
> +	    !((_key[0] ^ _key[4]) | (_key[1] ^ _key[5])))
> +		return -ENOKEY;

This introduces a sparse warning:

  CHECK   ../drivers/crypto/qce/skcipher.c
../drivers/crypto/qce/skcipher.c:241:58: warning: dubious: !x | !y
../drivers/crypto/qce/skcipher.c:242:58: warning: dubious: x | !y

Please make sure that you test your patches with C=1 so that
you don't introduce new sparse warnings.

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