iio: adc: meson-saradc: Variables could be uninitalized if regmap_read() fails
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Message ID 20190929164848.13930-1-yzhai003@ucr.edu
State Not Applicable
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Series
  • iio: adc: meson-saradc: Variables could be uninitalized if regmap_read() fails
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Commit Message

Yizhuo Sept. 29, 2019, 4:48 p.m. UTC
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@ucr.edu>
---
 drivers/iio/adc/meson_saradc.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

Comments

Martin Blumenstingl Sept. 30, 2019, 9:16 p.m. UTC | #1
Hi Yizhuo,

thank you for this patch

On Sun, Sep 29, 2019 at 6:48 PM Yizhuo <yzhai003@ucr.edu> wrote:
>
> 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.
the meson_saradc driver is using a MMIO regmap so read failures are
unlikely (unless there's a bug in the code somewhere)
did you find these issues with some static code analysis tool or did
you experience a real world problem?

> Signed-off-by: Yizhuo <yzhai003@ucr.edu>
> ---
>  drivers/iio/adc/meson_saradc.c | 30 ++++++++++++++++++++++++------
>  1 file changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
> index 7b28d045d271..4b6c2983ef39 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;
why not add "ret" to the variables in the line above?
so this could be shortened to (which is also consistent with the
coding style in meson_saradc):
  int ret, regval, timeout = 10000;

> @@ -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;
this is a big problem because we're returning with &indio_dev->mlock held
see the "timeout < 0" block below

> @@ -771,7 +782,7 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
>  {
>         struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
>         int regval, i, ret;
> -
> +       int ret;
this removes an empty line between the variable declarations and the
first code (comment)
also "ret" is already defined in the line before
(I haven't compile-tested this myself yet but I'm surprised that this
doesn't give an error or at least a warning)

> @@ -1013,8 +1027,12 @@ static irqreturn_t meson_sar_adc_irq(int irq, void *data)
>         struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
>         unsigned int cnt, threshold;
>         u32 regval;
> +       int ret;
> +
> +       ret = regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
> +       if (ret)
> +               return ret;
this function doesn't return "int" but irqreturn_t
the only allowed values are: [0]


Martin


[0] https://elixir.bootlin.com/linux/v5.3/source/include/linux/irqreturn.h#L11

Patch
diff mbox series

diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
index 7b28d045d271..4b6c2983ef39 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)
@@ -346,6 +349,7 @@  static int meson_sar_adc_read_raw_sample(struct iio_dev *indio_dev,
 {
 	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
 	int regval, fifo_chan, fifo_val, count;
+	int ret;
 
 	if(!wait_for_completion_timeout(&priv->done,
 				msecs_to_jiffies(MESON_SAR_ADC_TIMEOUT)))
@@ -358,7 +362,10 @@  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);
+	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) {
@@ -771,7 +782,7 @@  static int meson_sar_adc_init(struct iio_dev *indio_dev)
 {
 	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
 	int regval, i, ret;
-
+	int ret;
 	/*
 	 * make sure we start at CH7 input since the other muxes are only used
 	 * for internal calibration.
@@ -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;
 	}
@@ -1013,8 +1027,12 @@  static irqreturn_t meson_sar_adc_irq(int irq, void *data)
 	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
 	unsigned int cnt, threshold;
 	u32 regval;
+	int ret;
+
+	ret = regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
+	if (ret)
+		return ret;
 
-	regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
 	cnt = FIELD_GET(MESON_SAR_ADC_REG0_FIFO_COUNT_MASK, regval);
 	threshold = FIELD_GET(MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, regval);