linux-kernel - [PATCH] iio: adc: palmas: fix off by one bugs

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Date:   Fri, 21 Apr 2023 13:41:56 +0300
From:   Dan Carpenter <dan.carpenter@...aro.org>
To:     Patrik Dahlström <risca@...akolonin.se>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH] iio: adc: palmas: fix off by one bugs

Valid values for "adc_chan" are zero to (PALMAS_ADC_CH_MAX - 1).
Smatch detects some buffer overflows caused by this:
drivers/iio/adc/palmas_gpadc.c:721 palmas_gpadc_read_event_value() error: buffer overflow 'adc->thresholds' 16 <= 16
drivers/iio/adc/palmas_gpadc.c:758 palmas_gpadc_write_event_value() error: buffer overflow 'adc->thresholds' 16 <= 16

The effect of this bug in other functions is more complicated but
obviously we should fix all of them.

Fixes: a99544c6c883 ("iio: adc: palmas: add support for iio threshold events")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
---
 drivers/iio/adc/palmas_gpadc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/palmas_gpadc.c b/drivers/iio/adc/palmas_gpadc.c
index c1c439215aeb..7dfc9c927a23 100644
--- a/drivers/iio/adc/palmas_gpadc.c
+++ b/drivers/iio/adc/palmas_gpadc.c
@@ -547,7 +547,7 @@ static int palmas_gpadc_read_raw(struct iio_dev *indio_dev,
 	int adc_chan = chan->channel;
 	int ret = 0;
 
-	if (adc_chan > PALMAS_ADC_CH_MAX)
+	if (adc_chan >= PALMAS_ADC_CH_MAX)
 		return -EINVAL;
 
 	mutex_lock(&adc->lock);
@@ -595,7 +595,7 @@ static int palmas_gpadc_read_event_config(struct iio_dev *indio_dev,
 	int adc_chan = chan->channel;
 	int ret = 0;
 
-	if (adc_chan > PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
+	if (adc_chan >= PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
 		return -EINVAL;
 
 	mutex_lock(&adc->lock);
@@ -684,7 +684,7 @@ static int palmas_gpadc_write_event_config(struct iio_dev *indio_dev,
 	int adc_chan = chan->channel;
 	int ret;
 
-	if (adc_chan > PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
+	if (adc_chan >= PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
 		return -EINVAL;
 
 	mutex_lock(&adc->lock);
@@ -710,7 +710,7 @@ static int palmas_gpadc_read_event_value(struct iio_dev *indio_dev,
 	int adc_chan = chan->channel;
 	int ret;
 
-	if (adc_chan > PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
+	if (adc_chan >= PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
 		return -EINVAL;
 
 	mutex_lock(&adc->lock);
@@ -744,7 +744,7 @@ static int palmas_gpadc_write_event_value(struct iio_dev *indio_dev,
 	int old;
 	int ret;
 
-	if (adc_chan > PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
+	if (adc_chan >= PALMAS_ADC_CH_MAX || type != IIO_EV_TYPE_THRESH)
 		return -EINVAL;
 
 	mutex_lock(&adc->lock);
-- 
2.39.2