linux-kernel - Re: [PATCH] kernel/audit_tree.c: tree will memory leak when failure occurs for audit_trim

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Date:	Tue, 23 Apr 2013 09:46:50 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Eric Paris <eparis@...hat.com>, Al Viro <viro@...iv.linux.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kernel/audit_tree.c: tree will memory leak when failure
 occurs for audit_trim_trees()

On 2013年04月23日 07:04, Andrew Morton wrote:
> On Fri, 19 Apr 2013 17:39:06 +0800 Chen Gang <gang.chen@...anux.com> wrote:
> 
>>
>> in audit_trim_trees(), has called get_tree() before failure occurs,
>> so need also call put_tree after go to skip_it:
>>
>> ...
>>
>> --- a/kernel/audit_tree.c
>> +++ b/kernel/audit_tree.c
>> @@ -617,10 +617,10 @@ void audit_trim_trees(void)
>>  		}
>>  		spin_unlock(&hash_lock);
>>  		trim_marked(tree);
>> -		put_tree(tree);
>>  		drop_collected_mounts(root_mnt);
>>  skip_it:
>>  		mutex_lock(&audit_filter_mutex);
>> +		put_tree(tree);
>>  	}
>>  	list_del(&cursor);
>>  	mutex_unlock(&audit_filter_mutex);
> 
> That looks right to me.
> 
> I think we can micro-optimise the code by performing the put_tree()
> before taking the mutex, to slightly reduce mutex hold times?
> 

  ok, thanks.

> --- a/kernel/audit_tree.c~kernel-audit_treec-tree-will-leak-memory-when-failure-occurs-in-audit_trim_trees-fix
> +++ a/kernel/audit_tree.c
> @@ -619,8 +619,8 @@ void audit_trim_trees(void)
>  		trim_marked(tree);
>  		drop_collected_mounts(root_mnt);
>  skip_it:
> -		mutex_lock(&audit_filter_mutex);
>  		put_tree(tree);
> +		mutex_lock(&audit_filter_mutex);
>  	}
>  	list_del(&cursor);
>  	mutex_unlock(&audit_filter_mutex);
> _
> 
> 
> 
> 


-- 
Chen Gang

Asianux Corporation
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