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 22:52:50 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Eric Paris <eparis@...hat.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

On 2013年04月11日 22:34, Chen Gang wrote:
> On 2013年04月11日 21:40, Eric Paris wrote:
>>>> >> >   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.
>> > 

  oh.. it seems another issues need consider !!

    a. in function audit_remove_watch_rule, it does not set NULL for krule->watch.

    b. function audit_del_rule and audit_remove_watch_rule need lock protected.
         it seems we should call audit_del_rule in audit_free_rule.
           audit_del_rule will instead of audit_put_watch and audit_put_tree.
         but we need consider whether will cause dead lock !

       I will continue to see it.


>   I think:
>     it is in function audit_del_rule. when del, also set NULL.
>     so the deletion in audit_free_rule is safe.
>     the process of erule->watch and erule->tree are similar.
> 
>   please check, thanks.
> 
> 
>> > while(1)
>> >     auditctl -a exit,always -w /etc -F auid=-1
>> > 
>> > 
>> > 
>   it is valuable to me, thanks.
> 


-- 
Chen Gang

Asianux Corporation
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