Re: [PATCH] kernel: auditfilter: looping issue, memory leak if has2 or more AUDIT_FILTERKEYs

From: Chen Gang
Date: Thu Apr 11 2013 - 10:53:32 EST


On 2013å04æ11æ 22:34, Chen Gang wrote:
> On 2013å04æ11æ 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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