linux-kernel - Re: [PATCH v5 01/12] crypto: ecdsa - Convert byte arrays with key coordinates to digits

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Message-ID: <ZerPU6pJiosjOvDq@wunner.de>
Date: Fri, 8 Mar 2024 09:41:55 +0100
From: Lukas Wunner <lukas@...ner.de>
To: Stefan Berger <stefanb@...ux.ibm.com>
Cc: keyrings@...r.kernel.org, linux-crypto@...r.kernel.org,
	herbert@...dor.apana.org.au, davem@...emloft.net,
	linux-kernel@...r.kernel.org, saulo.alessandre@....jus.br
Subject: Re: [PATCH v5 01/12] crypto: ecdsa - Convert byte arrays with key
 coordinates to digits

On Wed, Mar 06, 2024 at 05:22:46PM -0500, Stefan Berger wrote:
> +static inline void ecc_digits_from_bytes(const u8 *in, unsigned int nbytes,
> +					 u64 *out, unsigned int ndigits)
> +{
> +	unsigned int o = nbytes & 7;
> +	u64 msd = 0;

My sincere apologies, I made a mistake when I proposed this:
It needs to be __be64 instead of u64...

> +
> +	if (o) {
> +		memcpy((u8 *)&msd + sizeof(msd) - o, in, o);
> +		out[--ndigits] = be64_to_cpu(msd);
> +		in += o;
> +	}

..otherwise sparse complains:

    crypto/ecdsa.c: note: in included file:
    >> include/crypto/internal/ecc.h:74:34: sparse: sparse: cast to restricted __be64
    >> include/crypto/internal/ecc.h:74:34: sparse: sparse: cast to restricted __be64
    [...]
    66	static inline void ecc_digits_from_bytes(const u8 *in, unsigned int nbytes,
    67						 u64 *out, unsigned int ndigits)
    68	{
    69		unsigned int o = nbytes & 7;
    70		u64 msd = 0;
    71	
    72		if (o) {
    73			memcpy((u8 *)&msd + sizeof(msd) - o, in, o);
  > 74			out[--ndigits] = be64_to_cpu(msd);
    75			in += o;
    76		}
    77		ecc_swap_digits(in, out, ndigits);
    78	}
    79	

0-day alerted me about this, it's monitoring my GitHub repo and
I've got your patches on one of my development branches.

Thanks,

Lukas