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

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Date:	Fri, 12 Apr 2013 17:42:20 +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 12:10, Chen Gang wrote:
> 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.
>>
>>

  it seems, your way is the only executable way (if not change code much).
  what my original idea is incorrect.

    we need add related code at failure process area in audit_data_to_entry.
    and another functions need not add these code (should not add).
    'watch' also need be processed, since audit_to_watch let ref count = 2.
      (it just like the function audit_del_rule has done)

  please help check thanks.

  :-)


diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 81f63f9..f5327ce 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -594,6 +594,10 @@ exit_nofree:
 	return entry;
 
 exit_free:
+	if (entry->rule.watch)
+		audit_put_watch(entry->rule.watch); /* matches initial get */
+	if (entry->rule.tree)
+		audit_put_tree(entry->rule.tree); /* that's the temporary one */
 	audit_free_rule(entry);
 	return ERR_PTR(err);
 }



> 
>   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];
> 
> 
>   thanks.
> 
>   :-)
> 


-- 
Chen Gang

Asianux Corporation
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