[PATCH v2] leds: ns2: Add of_node_put() before return

[PATCH v2] leds: ns2: Add of_node_put() before return

[Nishka Dasgupta]

Each iteration of for_each_child_of_node puts the previous node, but in
the case of a return from the middle of the loop, there is no put, thus
causing a memory leak. Hence create a new label, err_node_put, that puts
the previous node before returning the required value. Edit the mid-loop
return sites to instead go to this new label.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
---
Changes in v2:
- Put the of_node_put statement under a label instead of at each return
  site.
- Modify subject line to reflect previous patches on this driver.

 drivers/leds/leds-ns2.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/leds/leds-ns2.c b/drivers/leds/leds-ns2.c
index f92e2c07c1c6..83cdce0f801a 100644
--- a/drivers/leds/leds-ns2.c
+++ b/drivers/leds/leds-ns2.c
@@ -264,11 +264,11 @@ ns2_leds_get_of_pdata(struct device *dev, struct ns2_led_platform_data *pdata)
 
 		ret = of_get_named_gpio(child, "cmd-gpio", 0);
 		if (ret < 0)
-			return ret;
+			goto err_node_put;
 		led->cmd = ret;
 		ret = of_get_named_gpio(child, "slow-gpio", 0);
 		if (ret < 0)
-			return ret;
+			goto err_node_put;
 		led->slow = ret;
 		ret = of_property_read_string(child, "label", &string);
 		led->name = (ret == 0) ? string : child->name;
@@ -281,7 +281,8 @@ ns2_leds_get_of_pdata(struct device *dev, struct ns2_led_platform_data *pdata)
 		if (ret < 0 || ret % 3) {
 			dev_err(dev,
 				"Missing or malformed modes-map property\n");
-			return -EINVAL;
+			ret = -EINVAL;
+			goto err_node_put;
 		}
 
 		num_modes = ret / 3;
@@ -289,8 +290,10 @@ ns2_leds_get_of_pdata(struct device *dev, struct ns2_led_platform_data *pdata)
 				      num_modes,
 				      sizeof(struct ns2_led_modval),
 				      GFP_KERNEL);
-		if (!modval)
-			return -ENOMEM;
+		if (!modval) {
+			ret = -ENOMEM;
+			goto err_node_put;
+		}
 
 		for (i = 0; i < num_modes; i++) {
 			of_property_read_u32_index(child,
@@ -314,6 +317,10 @@ ns2_leds_get_of_pdata(struct device *dev, struct ns2_led_platform_data *pdata)
 	pdata->num_leds = num_leds;
 
 	return 0;
+
+err_node_put:
+	of_node_put(child);
+	return ret;
 }
 
 static const struct of_device_id of_ns2_leds_match[] = {
-- 
2.19.1

Re: [PATCH v2] leds: ns2: Add of_node_put() before return

[Jacek Anaszewski]

Hi Nishka,

Thank you for the update.

On 7/16/19 9:24 AM, Nishka Dasgupta wrote:
> Each iteration of for_each_child_of_node puts the previous node, but in
> the case of a return from the middle of the loop, there is no put, thus
> causing a memory leak. Hence create a new label, err_node_put, that puts
> the previous node before returning the required value. Edit the mid-loop
> return sites to instead go to this new label.
> Issue found with Coccinelle.
> 
> Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
> ---
> Changes in v2:
> - Put the of_node_put statement under a label instead of at each return
>   site.
> - Modify subject line to reflect previous patches on this driver.
> 
>  drivers/leds/leds-ns2.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/leds/leds-ns2.c b/drivers/leds/leds-ns2.c
> index f92e2c07c1c6..83cdce0f801a 100644
> --- a/drivers/leds/leds-ns2.c
> +++ b/drivers/leds/leds-ns2.c
> @@ -264,11 +264,11 @@ ns2_leds_get_of_pdata(struct device *dev, struct ns2_led_platform_data *pdata)
>  
>  		ret = of_get_named_gpio(child, "cmd-gpio", 0);
>  		if (ret < 0)
> -			return ret;
> +			goto err_node_put;
>  		led->cmd = ret;
>  		ret = of_get_named_gpio(child, "slow-gpio", 0);
>  		if (ret < 0)
> -			return ret;
> +			goto err_node_put;
>  		led->slow = ret;
>  		ret = of_property_read_string(child, "label", &string);
>  		led->name = (ret == 0) ? string : child->name;
> @@ -281,7 +281,8 @@ ns2_leds_get_of_pdata(struct device *dev, struct ns2_led_platform_data *pdata)
>  		if (ret < 0 || ret % 3) {
>  			dev_err(dev,
>  				"Missing or malformed modes-map property\n");
> -			return -EINVAL;
> +			ret = -EINVAL;
> +			goto err_node_put;
>  		}
>  
>  		num_modes = ret / 3;
> @@ -289,8 +290,10 @@ ns2_leds_get_of_pdata(struct device *dev, struct ns2_led_platform_data *pdata)
>  				      num_modes,
>  				      sizeof(struct ns2_led_modval),
>  				      GFP_KERNEL);
> -		if (!modval)
> -			return -ENOMEM;
> +		if (!modval) {
> +			ret = -ENOMEM;
> +			goto err_node_put;
> +		}
>  
>  		for (i = 0; i < num_modes; i++) {
>  			of_property_read_u32_index(child,
> @@ -314,6 +317,10 @@ ns2_leds_get_of_pdata(struct device *dev, struct ns2_led_platform_data *pdata)
>  	pdata->num_leds = num_leds;
>  
>  	return 0;
> +
> +err_node_put:
> +	of_node_put(child);
> +	return ret;

Now we're getting build break here since ret is declared only
inside the loop. I moved ret declaration to the top of the function
and applied. Thanks.

>  }
>  
>  static const struct of_device_id of_ns2_leds_match[] = {
>
-- 
Best regards,
Jacek Anaszewski