Re: [PATCH] leds: pca9532: check i2c_smbus_read_byte_data() return value

[Frank Li]

On Mon, Jul 27, 2026 at 05:57:54PM +0800, haibo.chen@xxxxxxxxxxx wrote:
> From: Haibo Chen <haibo.chen@xxxxxxx>
>
> Coverity report INTEGER_OVERFLOW (tainted_data_return ->
> cast_underflow -> overflow) in pca9532_getled().
> pca9532_getled() stored the return value of i2c_smbus_read_byte_data()
> into a char and used it directly to compute the LED state without
> checking for an error. i2c_smbus_read_byte_data() returns a negative
> error code on failure. On an I2C read error the negative value was
> assigned to an unsigned type, triggering an integer underflow/overflow,
> and a meaningless LED state was returned to the caller.
>
> Read the value into an int, check for the error, and fall back to
> PCA9532_OFF while emitting a warning when the read fails.
>
> Assisted-by: VeroCoder:vero-1 [cli]
> Signed-off-by: Haibo Chen <haibo.chen@xxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>  drivers/leds/leds-pca9532.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/leds/leds-pca9532.c b/drivers/leds/leds-pca9532.c
> index 2d37e00e459dee9f0313830f4852b01f40977311..e8ee17b8bd547a92372a8e74a6781b95ae831fe2 100644
> --- a/drivers/leds/leds-pca9532.c
> +++ b/drivers/leds/leds-pca9532.c
> @@ -298,12 +298,15 @@ static enum pca9532_state pca9532_getled(struct pca9532_led *led)
>  	struct i2c_client *client = led->client;
>  	struct pca9532_data *data = i2c_get_clientdata(client);
>  	u8 maxleds = data->chip_info->num_leds;
> -	char reg;
> -	enum pca9532_state ret;
> +	int reg;
> +	enum pca9532_state ret = PCA9532_OFF;
>
>  	mutex_lock(&data->update_lock);
>  	reg = i2c_smbus_read_byte_data(client, LED_REG(maxleds, led->id));
> -	ret = (reg & LED_MASK(led->id)) >> LED_SHIFT(led->id);
> +	if (reg >= 0)
> +		ret = (reg & LED_MASK(led->id)) >> LED_SHIFT(led->id);
> +	else
> +		dev_warn(&client->dev, "failed to read LED register: %d\n", reg);
>  	mutex_unlock(&data->update_lock);
>  	return ret;
>  }
>
> ---
> base-commit: c5e32e86ca02b003f86e095d379b38148999293d
> change-id: 20260727-led-fix-28f085e12feb
>
> Best regards,
> --
> Haibo Chen <haibo.chen@xxxxxxx>
>