iio: adc: ad7173: fix channels index for syscalib_mode

Fix the index used to look up the channel when accessing the
syscalib_mode attribute. The address field is a 0-based index (same
as scan_index) that it used to access the channel in the
ad7173_channels array throughout the driver. The channels field, on
the other hand, may not match the address field depending on the
channel configuration specified in the device tree and could result
in an out-of-bounds access.

Fixes: 031bdc8 ("iio: adc: ad7173: add calibration support")
Signed-off-by: David Lechner <[email protected]>
Link: https://patch.msgid.link/20250703-iio-adc-ad7173-fix-channels-index-for-syscalib_mode-v1-1-7fdaedb9cac0@baylibre.com
Cc: <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>

Author: dlech

drivers/iio/adc/ad7173.c

@@ -318,7 +318,7 @@ static int ad7173_set_syscalib_mode(struct iio_dev *indio_dev,
 {
 	struct ad7173_state *st = iio_priv(indio_dev);
 
-	st->channels[chan->channel].syscalib_mode = mode;
+	st->channels[chan->address].syscalib_mode = mode;
 
 	return 0;
 }
@@ -328,7 +328,7 @@ static int ad7173_get_syscalib_mode(struct iio_dev *indio_dev,
 {
 	struct ad7173_state *st = iio_priv(indio_dev);
 
-	return st->channels[chan->channel].syscalib_mode;
+	return st->channels[chan->address].syscalib_mode;
 }
 
 static ssize_t ad7173_write_syscalib(struct iio_dev *indio_dev,
@@ -347,7 +347,7 @@ static ssize_t ad7173_write_syscalib(struct iio_dev *indio_dev,
 	if (!iio_device_claim_direct(indio_dev))
 		return -EBUSY;
 
-	mode = st->channels[chan->channel].syscalib_mode;
+	mode = st->channels[chan->address].syscalib_mode;
 	if (sys_calib) {
 		if (mode == AD7173_SYSCALIB_ZERO_SCALE)
 			ret = ad_sd_calibrate(&st->sd, AD7173_MODE_CAL_SYS_ZERO,