Patchwork [net-next] net: sctp: sctp_auth_make_key_vector: remove duplicate ntohs calls

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Submitter Daniel Borkmann
Date Feb. 7, 2013, 11:41 a.m.
Message ID <c029f55f4d0bde790f77f62d623f4d1e387c4c0b.1360237025.git.dborkman@redhat.com>
Download mbox | patch
Permalink /patch/218895/
State Accepted
Delegated to: David Miller
Headers show

Comments

Daniel Borkmann - Feb. 7, 2013, 11:41 a.m.
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@redhat.com>
---
 net/sctp/auth.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)
Neil Horman - Feb. 7, 2013, 2:53 p.m.
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@redhat.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@tuxdriver.com>

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Vlad Yasevich - Feb. 7, 2013, 3:06 p.m.
On 02/07/2013 06:41 AM, 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@redhat.com>

Acked-by: Vlad Yasevich <vyasevich@gmail.com>

-vlad

> ---
>   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;
>   }
>

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David Miller - Feb. 8, 2013, 4:45 a.m.
From: Daniel Borkmann <dborkman@redhat.com>
Date: Thu,  7 Feb 2013 12:41:39 +0100

> 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@redhat.com>

Applied.
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Patch

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;
 }