2019-09-28 00:46:44

by Yizhuo Zhai

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

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 <[email protected]>
---
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

2019-09-28 06:58:08

by Nicholas Mc Guire

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

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 <[email protected]>

Just a few minor style issues - contentwise it look correct to me.
Reviewed-by: Nicholas Mc Guire <[email protected]>

> ---
> 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
>

2019-09-29 16:56:25

by Yizhuo Zhai

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

Hi Nicholas:

Thanks for your feedback, I made changes and submitted new patches
already. Check patch script generated a warning if I strictly align
the parameter with (. I checked other code inside this file and
modified the continuation accordingly.

On Fri, Sep 27, 2019 at 11:47 PM Nicholas Mc Guire <[email protected]> wrote:
>
> 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 <[email protected]>
>
> Just a few minor style issues - contentwise it look correct to me.
> Reviewed-by: Nicholas Mc Guire <[email protected]>
>
> > ---
> > 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
> >



--
Kind Regards,

Yizhuo Zhai

Computer Science, Graduate Student
University of California, Riverside