[PATCH v4] usb: roles: fix of node refcount leak in usb_role_switch_is_parent()

[PATCH v4] usb: roles: fix of node refcount leak in usb_role_switch_is_parent()

[Yang Yingliang]

I got the following report while doing device(mt6370-tcpc) load
test with CONFIG_OF_UNITTEST and CONFIG_OF_DYNAMIC enabled:

  OF: ERROR: memory leak, expected refcount 1 instead of 2,
  of_node_get()/of_node_put() unbalanced - destroy cset entry:
  attach overlay node /i2c/pmic@34

The 'parent' returned by fwnode_get_parent() with refcount incremented.
it needs be put after using.

Fixes: 6fadd72943b8 ("usb: roles: get usb-role-switch from parent")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
v2 -> v4:
  Remove not needed null pointer check.

v1 -> v2:
  Add description to how is the report generated.
---
 drivers/usb/roles/class.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
index dfaed7eee94f..32e6d19f7011 100644
--- a/drivers/usb/roles/class.c
+++ b/drivers/usb/roles/class.c
@@ -106,10 +106,13 @@ usb_role_switch_is_parent(struct fwnode_handle *fwnode)
 	struct fwnode_handle *parent = fwnode_get_parent(fwnode);
 	struct device *dev;
 
-	if (!parent || !fwnode_property_present(parent, "usb-role-switch"))
+	if (!fwnode_property_present(parent, "usb-role-switch")) {
+		fwnode_handle_put(parent);
 		return NULL;
+	}
 
 	dev = class_find_device_by_fwnode(role_class, parent);
+	fwnode_handle_put(parent);
 	return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
 }
 
-- 
2.25.1

Re: [PATCH v4] usb: roles: fix of node refcount leak in usb_role_switch_is_parent()

[Heikki Krogerus]

On Tue, Nov 22, 2022 at 07:12:26PM +0800, Yang Yingliang wrote:
> I got the following report while doing device(mt6370-tcpc) load
> test with CONFIG_OF_UNITTEST and CONFIG_OF_DYNAMIC enabled:
> 
>   OF: ERROR: memory leak, expected refcount 1 instead of 2,
>   of_node_get()/of_node_put() unbalanced - destroy cset entry:
>   attach overlay node /i2c/pmic@34
> 
> The 'parent' returned by fwnode_get_parent() with refcount incremented.
> it needs be put after using.
> 
> Fixes: 6fadd72943b8 ("usb: roles: get usb-role-switch from parent")
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
> v2 -> v4:
>   Remove not needed null pointer check.
> 
> v1 -> v2:
>   Add description to how is the report generated.
> ---
>  drivers/usb/roles/class.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
> index dfaed7eee94f..32e6d19f7011 100644
> --- a/drivers/usb/roles/class.c
> +++ b/drivers/usb/roles/class.c
> @@ -106,10 +106,13 @@ usb_role_switch_is_parent(struct fwnode_handle *fwnode)
>  	struct fwnode_handle *parent = fwnode_get_parent(fwnode);
>  	struct device *dev;
>  
> -	if (!parent || !fwnode_property_present(parent, "usb-role-switch"))
> +	if (!fwnode_property_present(parent, "usb-role-switch")) {
> +		fwnode_handle_put(parent);
>  		return NULL;
> +	}
>  
>  	dev = class_find_device_by_fwnode(role_class, parent);
> +	fwnode_handle_put(parent);
>  	return dev ? to_role_switch(dev) : ERR_PTR(-EPROBE_DEFER);
>  }
>  

thanks,

-- 
heikki