linux-kernel - Re: [PATCH 1/2] selinux: simple cleanup for cond_read

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Date:	Wed, 18 Jun 2014 15:36:22 -0400
From:	Paul Moore <paul@...l-moore.com>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Stephen Smalley <sds@...ho.nsa.gov>,
	Eric Paris <eparis@...isplace.org>, selinux@...ho.nsa.gov,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] selinux: simple cleanup for cond_read_node()

On Sunday, June 15, 2014 01:19:01 AM Namhyung Kim wrote:
> The node->cur_state and len can be read in a single call of next_entry().
> And setting len before reading is a dead write so can be eliminated.
> 
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  security/selinux/ss/conditional.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/security/selinux/ss/conditional.c
> b/security/selinux/ss/conditional.c index 377d148e7157..4766a38fae9a 100644
> --- a/security/selinux/ss/conditional.c
> +++ b/security/selinux/ss/conditional.c
> @@ -402,19 +402,14 @@ static int cond_read_node(struct policydb *p, struct
> cond_node *node, void *fp) int rc;
>  	struct cond_expr *expr = NULL, *last = NULL;
> 
> -	rc = next_entry(buf, fp, sizeof(u32));
> +	rc = next_entry(buf, fp, sizeof(buf));

This is a bit nit-picky, but how about using "sizeof(u32) * 2"?  It is more 
consistent with the rest of the function and helps underscore that we are 
reading two 32-bit values.

Assuming you're okay with the change I can fix it up when I apply the patch.

>  	if (rc)
>  		return rc;
> 
>  	node->cur_state = le32_to_cpu(buf[0]);
> 
> -	len = 0;
> -	rc = next_entry(buf, fp, sizeof(u32));
> -	if (rc)
> -		return rc;
> -
>  	/* expr */
> -	len = le32_to_cpu(buf[0]);
> +	len = le32_to_cpu(buf[1]);
> 
>  	for (i = 0; i < len; i++) {
>  		rc = next_entry(buf, fp, sizeof(u32) * 2);

-- 
paul moore
www.paul-moore.com

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