linux-kernel - Re: [PATCH] security: smack: fix memleak in smk_write_rules

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Date:	Thu, 01 Aug 2013 13:01:47 -0700
From:	Casey Schaufler <casey@...aufler-ca.com>
To:	Tomasz Stanislawski <t.stanislaws@...sung.com>
CC:	Casey Schaufler <casey@...aufler-ca.com>,
	linux-security-module@...r.kernel.org, m.szyprowski@...sung.com,
	kyungmin.park@...sung.com, r.krypa@...sung.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] security: smack: fix memleak in smk_write_rules_list()

On 6/19/2013 7:08 AM, Tomasz Stanislawski wrote:
> >From 8497987bedf8821db3dce47a6205dfce2b0895c5 Mon Sep 17 00:00:00 2001
> From: Tomasz Stanislawski <t.stanislaws@...sung.com>
> Date: Thu, 6 Jun 2013 09:30:50 +0200
> Subject: [PATCH] security: smack: fix memleak in smk_write_rules_list()
>
> The smack_parsed_rule structure is allocated.  If a rule is successfully
> installed then the last reference to the object is lost.  This patch fixes this
> leak. Moreover smack_parsed_rule is allocated on stack because it no longer
> needed ofter smk_write_rules_list() is finished.
>
> Signed-off-by: Tomasz Stanislawski <t.stanislaws@...sung.com>

Acked-by: Casey Schaufler <casey@...aufler-ca.com>


Applied to git://git.gitorious.org/smack-next/kernel.git#smack-for-3.12

Rebasing was required. The change has been tested.

> ---
>  security/smack/smackfs.c |   30 ++++++++++--------------------
>  1 file changed, 10 insertions(+), 20 deletions(-)
>
> diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
> index 53a08b8..08aebc2 100644
> --- a/security/smack/smackfs.c
> +++ b/security/smack/smackfs.c
> @@ -446,7 +446,7 @@ static ssize_t smk_write_rules_list(struct file *file, const char __user *buf,
>  					struct mutex *rule_lock, int format)
>  {
>  	struct smack_known *skp;
> -	struct smack_parsed_rule *rule;
> +	struct smack_parsed_rule rule;
>  	char *data;
>  	int datalen;
>  	int rc = -EINVAL;
> @@ -478,49 +478,39 @@ static ssize_t smk_write_rules_list(struct file *file, const char __user *buf,
>  		goto out;
>  	}
>
> -	rule = kzalloc(sizeof(*rule), GFP_KERNEL);
> -	if (rule == NULL) {
> -		rc = -ENOMEM;
> -		goto out;
> -	}
> -
>  	if (format == SMK_LONG_FMT) {
>  		/*
>  		 * Be sure the data string is terminated.
>  		 */
>  		data[count] = '\0';
> -		if (smk_parse_long_rule(data, rule, 1, 0))
> -			goto out_free_rule;
> +		if (smk_parse_long_rule(data, &rule, 1, 0))
> +			goto out;
>  	} else if (format == SMK_CHANGE_FMT) {
>  		data[count] = '\0';
> -		if (smk_parse_long_rule(data, rule, 1, 1))
> -			goto out_free_rule;
> +		if (smk_parse_long_rule(data, &rule, 1, 1))
> +			goto out;
>  	} else {
>  		/*
>  		 * More on the minor hack for backward compatibility
>  		 */
>  		if (count == (SMK_OLOADLEN))
>  			data[SMK_OLOADLEN] = '-';
> -		if (smk_parse_rule(data, rule, 1))
> -			goto out_free_rule;
> +		if (smk_parse_rule(data, &rule, 1))
> +			goto out;
>  	}
>
>
>  	if (rule_list == NULL) {
>  		load = 1;
> -		skp = smk_find_entry(rule->smk_subject);
> +		skp = smk_find_entry(rule.smk_subject);
>  		rule_list = &skp->smk_rules;
>  		rule_lock = &skp->smk_rules_lock;
>  	}
>
> -	rc = smk_set_access(rule, rule_list, rule_lock, load);
> -	if (rc == 0) {
> +	rc = smk_set_access(&rule, rule_list, rule_lock, load);
> +	if (rc == 0)
>  		rc = count;
> -		goto out;
> -	}
>
> -out_free_rule:
> -	kfree(rule);
>  out:
>  	kfree(data);
>  	return rc;

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