[PATCH] iio: adc: meson-saradc: Variables could be uninitalized if regmap_read() fails

From: Yizhuo
Date: Fri Sep 27 2019 - 20:46:12 EST


Several functions in this file are trying to use regmap_read() to
initialize the specific variable, however, if regmap_read() fails,
the variable could be uninitialized but used directly, which is
potentially unsafe. The return value of regmap_read() should be
checked and handled.

Signed-off-by: Yizhuo <yzhai003@xxxxxxx>
---
drivers/iio/adc/meson_saradc.c | 28 +++++++++++++++++++++++-----
1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
index 7b28d045d271..c032a64108b4 100644
--- a/drivers/iio/adc/meson_saradc.c
+++ b/drivers/iio/adc/meson_saradc.c
@@ -323,6 +323,7 @@ static int meson_sar_adc_wait_busy_clear(struct iio_dev *indio_dev)
{
struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
int regval, timeout = 10000;
+ int ret;

/*
* NOTE: we need a small delay before reading the status, otherwise
@@ -331,7 +332,9 @@ static int meson_sar_adc_wait_busy_clear(struct iio_dev *indio_dev)
*/
do {
udelay(1);
- regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
+ ret = regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
+ if (ret)
+ return ret;
} while (FIELD_GET(MESON_SAR_ADC_REG0_BUSY_MASK, regval) && timeout--);

if (timeout < 0)
@@ -358,7 +361,11 @@ static int meson_sar_adc_read_raw_sample(struct iio_dev *indio_dev,
return -EINVAL;
}

- regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &regval);
+ int ret = regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &regval);
+
+ if (ret)
+ return ret;
+
fifo_chan = FIELD_GET(MESON_SAR_ADC_FIFO_RD_CHAN_ID_MASK, regval);
if (fifo_chan != chan->address) {
dev_err(&indio_dev->dev,
@@ -491,6 +498,7 @@ static int meson_sar_adc_lock(struct iio_dev *indio_dev)
{
struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
int val, timeout = 10000;
+ int ret;

mutex_lock(&indio_dev->mlock);

@@ -506,7 +514,10 @@ static int meson_sar_adc_lock(struct iio_dev *indio_dev)
*/
do {
udelay(1);
- regmap_read(priv->regmap, MESON_SAR_ADC_DELAY, &val);
+ ret = regmap_read(priv->regmap,
+ MESON_SAR_ADC_DELAY, &val);
+ if (ret)
+ return ret;
} while (val & MESON_SAR_ADC_DELAY_BL30_BUSY && timeout--);

if (timeout < 0) {
@@ -784,7 +795,10 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
* BL30 to make sure BL30 gets the values it expects when
* reading the temperature sensor.
*/
- regmap_read(priv->regmap, MESON_SAR_ADC_REG3, &regval);
+ ret = regmap_read(priv->regmap, MESON_SAR_ADC_REG3, &regval);
+ if (ret)
+ return ret;
+
if (regval & MESON_SAR_ADC_REG3_BL30_INITIALIZED)
return 0;
}
@@ -1014,7 +1028,11 @@ static irqreturn_t meson_sar_adc_irq(int irq, void *data)
unsigned int cnt, threshold;
u32 regval;

- regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
+ int ret = regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
+
+ if (ret)
+ return ret;
+
cnt = FIELD_GET(MESON_SAR_ADC_REG0_FIFO_COUNT_MASK, regval);
threshold = FIELD_GET(MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, regval);

--
2.17.1