netdev - Re: [PATCH net-next] net: sctp: sctp_auth_make_key

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Date:	Thu, 7 Feb 2013 09:53:30 -0500
From:	Neil Horman <nhorman@...driver.com>
To:	Daniel Borkmann <dborkman@...hat.com>
Cc:	davem@...emloft.net, vyasevich@...il.com,
	linux-sctp@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] net: sctp: sctp_auth_make_key_vector: remove
 duplicate ntohs calls

On Thu, Feb 07, 2013 at 12:41:39PM +0100, Daniel Borkmann wrote:
> Instead of calling 3 times ntohs(random->param_hdr.length), 2 times
> ntohs(hmacs->param_hdr.length), and 3 times ntohs(chunks->param_hdr.length)
> within the same function, we only call each once and store it in a
> variable.
> 
> Signed-off-by: Daniel Borkmann <dborkman@...hat.com>
> ---
>  net/sctp/auth.c | 21 ++++++++++++---------
>  1 file changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/net/sctp/auth.c b/net/sctp/auth.c
> index 159b9bc..94a12de 100644
> --- a/net/sctp/auth.c
> +++ b/net/sctp/auth.c
> @@ -200,10 +200,14 @@ static struct sctp_auth_bytes *sctp_auth_make_key_vector(
>  	struct sctp_auth_bytes *new;
>  	__u32	len;
>  	__u32	offset = 0;
> +	__u16	random_len, hmacs_len, chunks_len = 0;
>  
> -	len = ntohs(random->param_hdr.length) + ntohs(hmacs->param_hdr.length);
> -        if (chunks)
> -		len += ntohs(chunks->param_hdr.length);
> +	random_len = ntohs(random->param_hdr.length);
> +	hmacs_len = ntohs(hmacs->param_hdr.length);
> +	if (chunks)
> +		chunks_len = ntohs(chunks->param_hdr.length);
> +
> +	len = random_len + hmacs_len + chunks_len;
>  
>  	new = kmalloc(sizeof(struct sctp_auth_bytes) + len, gfp);
>  	if (!new)
> @@ -211,16 +215,15 @@ static struct sctp_auth_bytes *sctp_auth_make_key_vector(
>  
>  	new->len = len;
>  
> -	memcpy(new->data, random, ntohs(random->param_hdr.length));
> -	offset += ntohs(random->param_hdr.length);
> +	memcpy(new->data, random, random_len);
> +	offset += random_len;
>  
>  	if (chunks) {
> -		memcpy(new->data + offset, chunks,
> -			ntohs(chunks->param_hdr.length));
> -		offset += ntohs(chunks->param_hdr.length);
> +		memcpy(new->data + offset, chunks, chunks_len);
> +		offset += chunks_len;
>  	}
>  
> -	memcpy(new->data + offset, hmacs, ntohs(hmacs->param_hdr.length));
> +	memcpy(new->data + offset, hmacs, hmacs_len);
>  
>  	return new;
>  }
> -- 
> 1.7.11.7
> 
> --
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> 
Acked-by: Neil Horman <nhorman@...driver.com>

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