linux-kernel - Re: [PATCH v3] of: dynamic: fix memory leak related to properties of __of_node

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Message-ID: <59E934A1.9060304@gmail.com>
Date:   Thu, 19 Oct 2017 16:26:25 -0700
From:   Frank Rowand <frowand.list@...il.com>
To:     Lixin Wang <alan.1.wang@...ia-sbell.com>,
        Rob Herring <robh+dt@...nel.org>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v3] of: dynamic: fix memory leak related to properties of
 __of_node_dup

Hi Lixin,

On 10/19/17 02:40, Lixin Wang wrote:
> If a node with no properties is dynamically added, then a property is
> dynamically added to the node, then the property is dynamically removed,
> the result will be node->properties == NULL and node->deadprops != NULL.
> 
> Add a separate function to release the properties in both lists.
> 
> Signed-off-by: Lixin Wang <alan.1.wang@...ia-sbell.com>
> ---
> v2 -> v3:
>  * Add a separate function to release the properties in both lists.
>  * Change the patch description for this change.
> 
>  drivers/of/dynamic.c | 27 +++++++++++++++------------
>  1 file changed, 15 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> index 301b6db..b28511f 100644
> --- a/drivers/of/dynamic.c
> +++ b/drivers/of/dynamic.c
> @@ -315,6 +315,19 @@ int of_detach_node(struct device_node *np)
>  }
>  EXPORT_SYMBOL_GPL(of_detach_node);
>  
> +static void __of_property_list_release(struct property *prop)
> +{
> +	struct property *next;
> +
> +	while (prop) {
> +		next = prop->next;
> +		kfree(prop->name);
> +		kfree(prop->value);
> +		kfree(prop);
> +		prop = next;
> +	}
> +}
> +
>  /**
>   * of_node_release() - release a dynamically allocated node
>   * @kref: kref element of the node to be released
> @@ -324,7 +337,6 @@ EXPORT_SYMBOL_GPL(of_detach_node);
>  void of_node_release(struct kobject *kobj)
>  {
>  	struct device_node *node = kobj_to_device_node(kobj);
> -	struct property *prop = node->properties;
>  
>  	/* We should never be releasing nodes that haven't been detached. */
>  	if (!of_node_check_flag(node, OF_DETACHED)) {
> @@ -335,18 +347,9 @@ void of_node_release(struct kobject *kobj)
>  	if (!of_node_check_flag(node, OF_DYNAMIC))
>  		return;
>  
> -	while (prop) {
> -		struct property *next = prop->next;
> -		kfree(prop->name);
> -		kfree(prop->value);
> -		kfree(prop);
> -		prop = next;
> +	__of_property_list_release(node->properties);
> +	__of_property_list_release(node->deadprops);
>  
> -		if (!prop) {
> -			prop = node->deadprops;
> -			node->deadprops = NULL;
> -		}
> -	}
>  	kfree(node->full_name);
>  	kfree(node->data);
>  	kfree(node);
> 

The code is correct, but I would prefer some style issues to be more
consistent with device tree code.  I will reply to this email with
an example patch that you can use.

-Frank