[PATCH v2 1/4] leds: pca9532: check i2c_smbus_read_byte_data() return value

From: Haibo Chen <[email protected]>

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.

Fixes: 28c5fe99016d ("leds: pca9532: Extend pca9532 device tree support")
Assisted-by: VeroCoder:claude-sonnet-4
Signed-off-by: Haibo Chen <[email protected]>
---
 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;
 }

-- 
2.34.1