linux-kernel - Re: [PATCH] kernel: auditfilter: looping issue, memory leak if has 2 or more AUDIT

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Date:	Thu, 11 Apr 2013 09:40:29 -0400 (EDT)
From:	Eric Paris <eparis@...hat.com>
To:	Chen Gang <gang.chen@...anux.com>
Cc:	Al Viro <viro@...iv.linux.org.uk>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kernel: auditfilter: looping issue, memory leak if has
 2 or more AUDIT_FILTERKEYs

----- Original Message -----
> On 2013年04月11日 05:19, Eric Paris wrote:
> > ----- Original Message -----
> > 
> >> >   b. has an new issue for AUDIT_DIR:
> >> >        after AUDIT_DIR succeed, it will set rule->tree.
> >> >        next, the other case fail, then will call audit_free_rule.
> >> >        but audit_free_rule will not free rule->tree.
> > Definitely a couple of leaks here...
> > 
> > I'm seeing leaks on size 8, 64, and 128.
> > 
> > Al, what do you think?  Should I be calling audit_put_tree() in the error
> > case if entry->tree != NULL?  The audit trees are some of the most complex
> > code in the kernel I think.
> > 
> > 
> 
>   can we add it in audit_free_rule ?
> 
>   maybe like this:
> 
> @@ -75,6 +75,8 @@ static inline void audit_free_rule(struct audit_entry *e)
>  	/* some rules don't have associated watches */
>  	if (erule->watch)
>  		audit_put_watch(erule->watch);
> +	if (erule->tree)
> +		audit_put_tree(erule->tree);
>  	if (erule->fields)
>  		for (i = 0; i < erule->field_count; i++) {
>  			struct audit_field *f = &erule->fields[i];

Where does the tree information get freed normally?  That's the code you need to run down.  You don't want to start getting double frees on the non-error case.  I'll try to dig into it if Al doesn't.  It's easy to show the leak on current kernels.

while(1)
    auditctl -a exit,always -w /etc -F auid=-1

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