Re: [PATCH] thermal/drivers/rcar: add error checking in probe()

[Niklas Söderlund]

Hi Dan,

Thanks for your work.

On 2026-06-23 10:49:29 +0300, Dan Carpenter wrote:
> The thermal_zone_device_register_with_trips() can fail for a number of
> reasons, including allocation failures.  Check for error pointers to
> avoid an error pointer dereference.
> 
> Fixes: 9d617949d490 ("thermal/drivers/renesas: Group all renesas thermal drivers together")

I don't think this is correct as this commits just moves the file.

> Signed-off-by: Dan Carpenter <error27@xxxxxxxxx>
> ---
>  drivers/thermal/renesas/rcar_thermal.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/thermal/renesas/rcar_thermal.c b/drivers/thermal/renesas/rcar_thermal.c
> index 6e5dcac5d47a..71f836fbc698 100644
> --- a/drivers/thermal/renesas/rcar_thermal.c
> +++ b/drivers/thermal/renesas/rcar_thermal.c
> @@ -492,6 +492,11 @@ static int rcar_thermal_probe(struct platform_device *pdev)
>  				"rcar_thermal", trips, ARRAY_SIZE(trips), priv,
>  						&rcar_thermal_zone_ops, NULL, 0,
>  						idle);
> +			if (IS_ERR(priv->zone)) {
> +				ret = PTR_ERR(priv->zone);
> +				priv->zone = NULL;
> +				goto error_unregister;
> +			}

While this indeed is an issue that should be fixed I don't think this is 
the correct fix. Below the if .. else .. block where this is added there 
already is a check for IS_ERR(priv->zone). That however does not guard 
against the usage of priv->zone for thermal_zone_device_enable().

We should only call thermal_zone_device_enable() if we are on a system 
that uses OF (gated by chip->use_of_thermal) which is the reason for the 
if .. else .. block in the first place. As chance have it we also have a 
check on chip->use_of_thermal directly after the existing 
IS_ERR(priv->zone) check. I think it would be better to move the call to 
thermal_zone_device_enable() there and avoid having two checks for 
IS_ERR(priv->zone)? Something like this,

diff --git a/drivers/thermal/renesas/rcar_thermal.c b/drivers/thermal/renesas/rcar_thermal.c
index 6e5dcac5d47a..dd13cf971ddb 100644
--- a/drivers/thermal/renesas/rcar_thermal.c
+++ b/drivers/thermal/renesas/rcar_thermal.c
@@ -492,12 +492,6 @@ static int rcar_thermal_probe(struct platform_device *pdev)
 				"rcar_thermal", trips, ARRAY_SIZE(trips), priv,
 						&rcar_thermal_zone_ops, NULL, 0,
 						idle);
-
-			ret = thermal_zone_device_enable(priv->zone);
-			if (ret) {
-				thermal_zone_device_unregister(priv->zone);
-				priv->zone = ERR_PTR(ret);
-			}
 		}
 		if (IS_ERR(priv->zone)) {
 			dev_err(dev, "can't register thermal zone\n");
@@ -507,13 +501,16 @@ static int rcar_thermal_probe(struct platform_device *pdev)
 		}

 		if (chip->use_of_thermal) {
+			ret = thermal_zone_device_enable(priv->zone);
+			if (ret)
+				goto error_of_thermal;
+
 			ret = thermal_add_hwmon_sysfs(priv->zone);
 			if (ret)
-				goto error_unregister;
+				goto error_of_thermal;
 		}

 		rcar_thermal_irq_enable(priv);
-
 		list_move_tail(&priv->list, &common->head);

 		/* update ENR bits */
@@ -528,6 +525,8 @@ static int rcar_thermal_probe(struct platform_device *pdev)

 	return 0;

+error_of_thermal:
+	thermal_zone_device_unregister(priv->zone);
 error_unregister:
 	rcar_thermal_remove(pdev);

>  
>  			ret = thermal_zone_device_enable(priv->zone);
>  			if (ret) {
> -- 
> 2.53.0
> 

-- 
Kind Regards,
Niklas Söderlund