linux-kernel - Re: [PATCH v3] device property: fix of node refcount leak in fwnode_graph_get_next

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Message-ID: <d2c7979e-3891-283e-d20b-97b75a27730e@gmail.com>
Date:   Fri, 25 Nov 2022 09:32:56 +0000
From:   Daniel Scally <djrscally@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Yang Yingliang <yangyingliang@...wei.com>
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        heikki.krogerus@...ux.intel.com, sakari.ailus@...ux.intel.com,
        gregkh@...uxfoundation.org, rafael@...nel.org
Subject: Re: [PATCH v3] device property: fix of node refcount leak in
 fwnode_graph_get_next_endpoint()

Hello

On 23/11/2022 13:31, Andy Shevchenko wrote:
> On Wed, Nov 23, 2022 at 10:25:42AM +0800, Yang Yingliang wrote:
>> The 'parent' returned by fwnode_graph_get_port_parent()
>> with refcount incremented when 'prev' is not NULL, it
>> needs be put when finish using it.
>>
>> Because the parent is const, introduce a new variable to
>> store the returned fwnode, then put it before returning
>> from fwnode_graph_get_next_endpoint().
> To me this looks good enough. Not sure if Dan has a chance (time) to look at
> this, though. And maybe even test...
>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>


Apologies; didn't notice this earlier. I will look at and test this today

>
>> Fixes: b5b41ab6b0c1 ("device property: Check fwnode->secondary in fwnode_graph_get_next_endpoint()")
>> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
>> ---
>> v2 -> v3:
>>   Add a out label.
>>
>> v1 -> v2:
>>   Introduce a new variable to store the returned fwnode.
>> ---
>>  drivers/base/property.c | 18 ++++++++++++------
>>  1 file changed, 12 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/base/property.c b/drivers/base/property.c
>> index 2a5a37fcd998..7f338cb4fb7b 100644
>> --- a/drivers/base/property.c
>> +++ b/drivers/base/property.c
>> @@ -989,26 +989,32 @@ struct fwnode_handle *
>>  fwnode_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
>>  			       struct fwnode_handle *prev)
>>  {
>> +	struct fwnode_handle *ep, *port_parent = NULL;
>>  	const struct fwnode_handle *parent;
>> -	struct fwnode_handle *ep;
>>  
>>  	/*
>>  	 * If this function is in a loop and the previous iteration returned
>>  	 * an endpoint from fwnode->secondary, then we need to use the secondary
>>  	 * as parent rather than @fwnode.
>>  	 */
>> -	if (prev)
>> -		parent = fwnode_graph_get_port_parent(prev);
>> -	else
>> +	if (prev) {
>> +		port_parent = fwnode_graph_get_port_parent(prev);
>> +		parent = port_parent;
>> +	} else {
>>  		parent = fwnode;
>> +	}
>>  	if (IS_ERR_OR_NULL(parent))
>>  		return NULL;
>>  
>>  	ep = fwnode_call_ptr_op(parent, graph_get_next_endpoint, prev);
>>  	if (ep)
>> -		return ep;
>> +		goto out_put_port_parent;
>> +
>> +	ep = fwnode_graph_get_next_endpoint(parent->secondary, NULL);
>>  
>> -	return fwnode_graph_get_next_endpoint(parent->secondary, NULL);
>> +out_put_port_parent:
>> +	fwnode_handle_put(port_parent);
>> +	return ep;
>>  }
>>  EXPORT_SYMBOL_GPL(fwnode_graph_get_next_endpoint);
>>  
>> -- 
>> 2.25.1
>>