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

[Nicholas Mc Guire]

On Fri, Sep 27, 2019 at 05:46:41PM -0700, Yizhuo 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.
> 
> Signed-off-by: Yizhuo <yzhai...@ucr.edu>

Just a few minor style issues - contentwise it look correct to me.
Reviewed-by: Nicholas Mc Guire <hof...@osadl.org>

> ---
>  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,

any reason not to declear ret in the declaration block ?
so just for consistency with coding style within meson_saradc.c
this might be:

        int regval, fifo_chan, fifo_val, count;
+       int ret;

>               return -EINVAL;
>       }
>  
> -     regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &regval);
> +     int ret = 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);

checkpatch does not fuss here but the continuation should be alligned
witht the ( here

> +                     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;

same as above

+       int ret;

>  
> -     regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);
> +     int ret = regmap_read(priv->regmap, MESON_SAR_ADC_REG0, &regval);

+       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
>