backlight: qcom-wled: Add NULL check in the wled_configure

[PATCH] backlight: qcom-wled: Add NULL check in the wled_configure

Posted by Henry Martin 8 months, 3 weeks ago

When devm_kasprintf() fails, it returns a NULL pointer. However, this return value is not properly checked in the function wled_configure.

A NULL check should be added after the devm_kasprintf call to prevent potential NULL pointer dereference error.

Fixes: f86b77583d88c ("backlight: pm8941: Convert to using %pOFn instead of device_node.name")

Signed-off-by: Henry Martin <bsdhenrymartin@gmail.com>
---
 drivers/video/backlight/qcom-wled.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index 9afe701b2a1b..db5eda8ec37e 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -1406,8 +1406,14 @@ static int wled_configure(struct wled *wled)
 	wled->ctrl_addr = be32_to_cpu(*prop_addr);
 
 	rc = of_property_read_string(dev->of_node, "label", &wled->name);
-	if (rc)
+	if (rc) {
 		wled->name = devm_kasprintf(dev, GFP_KERNEL, "%pOFn", dev->of_node);
+		if (!wled->name) {
+			dev_err(dev, "Failed to allocate memory for wled name\n");
+			return -ENOMEM;
+		}
+	}
+
 
 	switch (wled->version) {
 	case 3:
-- 
2.34.1

Re: [PATCH] backlight: qcom-wled: Add NULL check in the wled_configure

Posted by Markus Elfring 8 months, 3 weeks ago

> When devm_kasprintf() fails, it returns a NULL pointer. However, this return value is not properly checked in the function wled_configure.
>
> A NULL check should be added after the devm_kasprintf call to prevent potential NULL pointer dereference error.

* Please adhere to word wrapping preferences around 75 characters per text line.

* How do you think about to choose the imperative mood for an improved change description?
  https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.14#n94


…
> +++ b/drivers/video/backlight/qcom-wled.c
> @@ -1406,8 +1406,14 @@ static int wled_configure(struct wled *wled)
>  	wled->ctrl_addr = be32_to_cpu(*prop_addr);
>
>  	rc = of_property_read_string(dev->of_node, "label", &wled->name);
> -	if (rc)
> +	if (rc) {
>  		wled->name = devm_kasprintf(dev, GFP_KERNEL, "%pOFn", dev->of_node);
> +		if (!wled->name) {
> +			dev_err(dev, "Failed to allocate memory for wled name\n");
> +			return -ENOMEM;
> +		}
> +	}
…

An extra error messages for a failed memory allocation may occasionally be omitted.

Regards,
Markus

Re: [PATCH] backlight: qcom-wled: Add NULL check in the wled_configure

Posted by Daniel Thompson 8 months, 3 weeks ago

On Mon, Mar 31, 2025 at 05:12:45PM +0800, Henry Martin wrote:
> When devm_kasprintf() fails, it returns a NULL pointer. However, this return value is not properly checked in the function wled_configure.
>
> A NULL check should be added after the devm_kasprintf call to prevent potential NULL pointer dereference error.
>
> Fixes: f86b77583d88c ("backlight: pm8941: Convert to using %pOFn instead of device_node.name")
>
> Signed-off-by: Henry Martin <bsdhenrymartin@gmail.com>
> ---
>  drivers/video/backlight/qcom-wled.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
> index 9afe701b2a1b..db5eda8ec37e 100644
> --- a/drivers/video/backlight/qcom-wled.c
> +++ b/drivers/video/backlight/qcom-wled.c
> @@ -1406,8 +1406,14 @@ static int wled_configure(struct wled *wled)
>  	wled->ctrl_addr = be32_to_cpu(*prop_addr);
>
>  	rc = of_property_read_string(dev->of_node, "label", &wled->name);
> -	if (rc)
> +	if (rc) {
>  		wled->name = devm_kasprintf(dev, GFP_KERNEL, "%pOFn", dev->of_node);
> +		if (!wled->name) {
> +			dev_err(dev, "Failed to allocate memory for wled name\n");
> +			return -ENOMEM;
> +		}
> +	}
> +

No objections to the check but I don't think it needs a dev_err(). It
is a waste of .text to store a string that is likely never to be
printed.


Daniel.