iio: inv_mpu6050: Fully validate gyro and accel scale writes

When setting the gyro or accelerometer scale the inv_mpu6050 driver ignores
the integer part of the value. As a result e.g. all of 0.13309, 1.13309,
12345.13309, ... are accepted as a valid gyro scale and 0.13309 is the
scale that gets set in all those cases.

Make sure to check that the integer part of the scale value is 0 and reject
it otherwise.

Fixes: 09a642b785 ("Invensense MPU6050 Device Driver.")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
Link: https://lore.kernel.org/r/20210405114441.24167-1-lars@metafoo.de
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/inv_mpu6050/inv_mpu_core.c

@@ -731,12 +731,16 @@ inv_mpu6050_read_raw(struct iio_dev *indio_dev,
 	}
 }
 
-static int inv_mpu6050_write_gyro_scale(struct inv_mpu6050_state *st, int val)
+static int inv_mpu6050_write_gyro_scale(struct inv_mpu6050_state *st, int val,
+					int val2)
 {
 	int result, i;
 
+	if (val != 0)
+		return -EINVAL;
+
 	for (i = 0; i < ARRAY_SIZE(gyro_scale_6050); ++i) {
-		if (gyro_scale_6050[i] == val) {
+		if (gyro_scale_6050[i] == val2) {
 			result = inv_mpu6050_set_gyro_fsr(st, i);
 			if (result)
 				return result;
@@ -767,13 +771,17 @@ static int inv_write_raw_get_fmt(struct iio_dev *indio_dev,
 	return -EINVAL;
 }
 
-static int inv_mpu6050_write_accel_scale(struct inv_mpu6050_state *st, int val)
+static int inv_mpu6050_write_accel_scale(struct inv_mpu6050_state *st, int val,
+					 int val2)
 {
 	int result, i;
 	u8 d;
 
+	if (val != 0)
+		return -EINVAL;
+
 	for (i = 0; i < ARRAY_SIZE(accel_scale); ++i) {
-		if (accel_scale[i] == val) {
+		if (accel_scale[i] == val2) {
 			d = (i << INV_MPU6050_ACCL_CONFIG_FSR_SHIFT);
 			result = regmap_write(st->map, st->reg->accl_config, d);
 			if (result)
@@ -814,10 +822,10 @@ static int inv_mpu6050_write_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->type) {
 		case IIO_ANGL_VEL:
-			result = inv_mpu6050_write_gyro_scale(st, val2);
+			result = inv_mpu6050_write_gyro_scale(st, val, val2);
 			break;
 		case IIO_ACCEL:
-			result = inv_mpu6050_write_accel_scale(st, val2);
+			result = inv_mpu6050_write_accel_scale(st, val, val2);
 			break;
 		default:
 			result = -EINVAL;