2022-05-18 06:53:49

by Yongzhi Liu

Subject: [PATCH] iio: vadc: Fix potential dereference of NULL pointer

The return value of vadc_get_channel() needs to be checked
to avoid use of NULL pointer, which is followed by
the caller 'vadc_do_conversion' of function 'vadc_configure'.
Fix this by adding the null pointer check on prop
in function 'vadc_configure'.

Signed-off-by: Yongzhi Liu <[email protected]>
---
drivers/iio/adc/qcom-spmi-vadc.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/iio/adc/qcom-spmi-vadc.c b/drivers/iio/adc/qcom-spmi-vadc.c
index 34202ba..d99bd72 100644
--- a/drivers/iio/adc/qcom-spmi-vadc.c
+++ b/drivers/iio/adc/qcom-spmi-vadc.c
@@ -210,6 +210,9 @@ static int vadc_configure(struct vadc_priv *vadc,
u8 decimation, mode_ctrl;
int ret;

+ if (!prop)
+ return -ENODEV;
+
/* Mode selection */
mode_ctrl = (VADC_OP_MODE_NORMAL << VADC_OP_MODE_SHIFT) |
VADC_ADC_TRIM_EN | VADC_AMUX_TRIM_EN;
--
2.7.4

2022-05-18 17:34:20

by Matthias Kaehlcke

Subject: Re: [PATCH] iio: vadc: Fix potential dereference of NULL pointer

On Tue, May 17, 2022 at 11:43:00PM -0700, Yongzhi Liu wrote:
> The return value of vadc_get_channel() needs to be checked
> to avoid use of NULL pointer, which is followed by
> the caller 'vadc_do_conversion' of function 'vadc_configure'.
> Fix this by adding the null pointer check on prop
> in function 'vadc_configure'.
>
> Signed-off-by: Yongzhi Liu <[email protected]>
> ---
> drivers/iio/adc/qcom-spmi-vadc.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/iio/adc/qcom-spmi-vadc.c b/drivers/iio/adc/qcom-spmi-vadc.c
> index 34202ba..d99bd72 100644
> --- a/drivers/iio/adc/qcom-spmi-vadc.c
> +++ b/drivers/iio/adc/qcom-spmi-vadc.c
> @@ -210,6 +210,9 @@ static int vadc_configure(struct vadc_priv *vadc,
> u8 decimation, mode_ctrl;
> int ret;
>
> + if (!prop)
> + return -ENODEV;
> +
> /* Mode selection */
> mode_ctrl = (VADC_OP_MODE_NORMAL << VADC_OP_MODE_SHIFT) |
> VADC_ADC_TRIM_EN | VADC_AMUX_TRIM_EN;


Shouldn't the check be done in vadc_measure_ref_points() where 'prop' is
obtained, rather than deep down in the call chain? For example
vadc_do_conversion() would also dereference the NULL pointer unless one
of the prior function calls fails.

2022-05-19 08:40:32

by Yongzhi Liu

Subject: [PATCH v2] iio: vadc: Fix potential dereference of NULL pointer

The return value of vadc_get_channel() needs to be checked
to avoid use of NULL pointer. Fix this by adding the null
pointer check on prop.

Fixes: 0917de94c ("iio: vadc: Qualcomm SPMI PMIC voltage ADC driver")

Signed-off-by: Yongzhi Liu <[email protected]>
---
drivers/iio/adc/qcom-spmi-vadc.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/qcom-spmi-vadc.c b/drivers/iio/adc/qcom-spmi-vadc.c
index 34202ba..9fa61fb 100644
--- a/drivers/iio/adc/qcom-spmi-vadc.c
+++ b/drivers/iio/adc/qcom-spmi-vadc.c
@@ -358,14 +358,25 @@ static int vadc_measure_ref_points(struct vadc_priv *vadc)
vadc->graph[VADC_CALIB_ABSOLUTE].dx = VADC_ABSOLUTE_RANGE_UV;

prop = vadc_get_channel(vadc, VADC_REF_1250MV);
+ if (!prop) {
+ dev_err(vadc->dev, "Please define 1.25V channel\n");
+ ret = -ENODEV;
+ goto err;
+ }
ret = vadc_do_conversion(vadc, prop, &read_1);
if (ret)
goto err;

/* Try with buffered 625mV channel first */
prop = vadc_get_channel(vadc, VADC_SPARE1);
- if (!prop)
+ if (!prop) {
prop = vadc_get_channel(vadc, VADC_REF_625MV);
+ if (!prop) {
+ dev_err(vadc->dev, "Please define 0.625V channel\n");
+ ret = -ENODEV;
+ goto err;
+ }
+ }

ret = vadc_do_conversion(vadc, prop, &read_2);
if (ret)
@@ -381,11 +392,21 @@ static int vadc_measure_ref_points(struct vadc_priv *vadc)

/* Ratiometric calibration */
prop = vadc_get_channel(vadc, VADC_VDD_VADC);
+ if (!prop) {
+ dev_err(vadc->dev, "Please define VDD channel\n");
+ ret = -ENODEV;
+ goto err;
+ }
ret = vadc_do_conversion(vadc, prop, &read_1);
if (ret)
goto err;

prop = vadc_get_channel(vadc, VADC_GND_REF);
+ if (!prop) {
+ dev_err(vadc->dev, "Please define GND channel\n");
+ ret = -ENODEV;
+ goto err;
+ }
ret = vadc_do_conversion(vadc, prop, &read_2);
if (ret)
goto err;
--
2.7.4

2022-05-23 07:03:16

by Jonathan Cameron

Subject: Re: [PATCH v2] iio: vadc: Fix potential dereference of NULL pointer

On Wed, 18 May 2022 22:50:55 -0700
Yongzhi Liu <[email protected]> wrote:

> The return value of vadc_get_channel() needs to be checked
> to avoid use of NULL pointer. Fix this by adding the null
> pointer check on prop.
>
> Fixes: 0917de94c ("iio: vadc: Qualcomm SPMI PMIC voltage ADC driver")
>
> Signed-off-by: Yongzhi Liu <[email protected]>
This function has a lot of goto err; where err just results in
a print.

My suggestion is to just drop that print and use
error specific prints as you have done here, then use direct returns.

> ---
> drivers/iio/adc/qcom-spmi-vadc.c | 23 ++++++++++++++++++++++-
> 1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/adc/qcom-spmi-vadc.c b/drivers/iio/adc/qcom-spmi-vadc.c
> index 34202ba..9fa61fb 100644
> --- a/drivers/iio/adc/qcom-spmi-vadc.c
> +++ b/drivers/iio/adc/qcom-spmi-vadc.c
> @@ -358,14 +358,25 @@ static int vadc_measure_ref_points(struct vadc_priv *vadc)
> vadc->graph[VADC_CALIB_ABSOLUTE].dx = VADC_ABSOLUTE_RANGE_UV;
>
> prop = vadc_get_channel(vadc, VADC_REF_1250MV);
> + if (!prop) {
> + dev_err(vadc->dev, "Please define 1.25V channel\n");
> + ret = -ENODEV;
> + goto err;
> + }
> ret = vadc_do_conversion(vadc, prop, &read_1);
> if (ret)
> goto err;
>
> /* Try with buffered 625mV channel first */
> prop = vadc_get_channel(vadc, VADC_SPARE1);
> - if (!prop)
> + if (!prop) {
> prop = vadc_get_channel(vadc, VADC_REF_625MV);
> + if (!prop) {
> + dev_err(vadc->dev, "Please define 0.625V channel\n");
> + ret = -ENODEV;
> + goto err;
> + }
> + }
>
> ret = vadc_do_conversion(vadc, prop, &read_2);
> if (ret)
> @@ -381,11 +392,21 @@ static int vadc_measure_ref_points(struct vadc_priv *vadc)
>
> /* Ratiometric calibration */
> prop = vadc_get_channel(vadc, VADC_VDD_VADC);
> + if (!prop) {
> + dev_err(vadc->dev, "Please define VDD channel\n");
> + ret = -ENODEV;
> + goto err;
> + }
> ret = vadc_do_conversion(vadc, prop, &read_1);
> if (ret)
> goto err;
>
> prop = vadc_get_channel(vadc, VADC_GND_REF);
> + if (!prop) {
> + dev_err(vadc->dev, "Please define GND channel\n");
> + ret = -ENODEV;
> + goto err;
> + }
> ret = vadc_do_conversion(vadc, prop, &read_2);
> if (ret)
> goto err;

2022-05-23 08:12:36

by Yongzhi Liu

Subject: [PATCH v3] iio: vadc: Fix potential dereference of NULL pointer

The return value of vadc_get_channel() needs to be checked to
avoid use of NULL pointer. Fix this by adding the null pointer
check on prop and dropping general error prints.

Fixes: 0917de94c02f ("iio: vadc: Qualcomm SPMI PMIC voltage ADC driver")
Signed-off-by: Yongzhi Liu <[email protected]>
---
drivers/iio/adc/qcom-spmi-vadc.c | 38 ++++++++++++++++++++++++++++----------
1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/adc/qcom-spmi-vadc.c b/drivers/iio/adc/qcom-spmi-vadc.c
index 34202ba..43a52b1 100644
--- a/drivers/iio/adc/qcom-spmi-vadc.c
+++ b/drivers/iio/adc/qcom-spmi-vadc.c
@@ -358,22 +358,33 @@ static int vadc_measure_ref_points(struct vadc_priv *vadc)
vadc->graph[VADC_CALIB_ABSOLUTE].dx = VADC_ABSOLUTE_RANGE_UV;

prop = vadc_get_channel(vadc, VADC_REF_1250MV);
+ if (!prop) {
+ dev_err(vadc->dev, "Please define 1.25V channel\n");
+ ret = -ENODEV;
+ return ret;
+ }
ret = vadc_do_conversion(vadc, prop, &read_1);
if (ret)
- goto err;
+ return ret;

/* Try with buffered 625mV channel first */
prop = vadc_get_channel(vadc, VADC_SPARE1);
- if (!prop)
+ if (!prop) {
prop = vadc_get_channel(vadc, VADC_REF_625MV);
+ if (!prop) {
+ dev_err(vadc->dev, "Please define 0.625V channel\n");
+ ret = -ENODEV;
+ return ret;
+ }
+ }

ret = vadc_do_conversion(vadc, prop, &read_2);
if (ret)
- goto err;
+ return ret;

if (read_1 == read_2) {
ret = -EINVAL;
- goto err;
+ return ret;
}

vadc->graph[VADC_CALIB_ABSOLUTE].dy = read_1 - read_2;
@@ -381,25 +392,32 @@ static int vadc_measure_ref_points(struct vadc_priv *vadc)

/* Ratiometric calibration */
prop = vadc_get_channel(vadc, VADC_VDD_VADC);
+ if (!prop) {
+ dev_err(vadc->dev, "Please define VDD channel\n");
+ ret = -ENODEV;
+ return ret;
+ }
ret = vadc_do_conversion(vadc, prop, &read_1);
if (ret)
- goto err;
+ return ret;

prop = vadc_get_channel(vadc, VADC_GND_REF);
+ if (!prop) {
+ dev_err(vadc->dev, "Please define GND channel\n");
+ ret = -ENODEV;
+ return ret;
+ }
ret = vadc_do_conversion(vadc, prop, &read_2);
if (ret)
- goto err;
+ return ret;

if (read_1 == read_2) {
ret = -EINVAL;
- goto err;
+ return ret;
}

vadc->graph[VADC_CALIB_RATIOMETRIC].dy = read_1 - read_2;
vadc->graph[VADC_CALIB_RATIOMETRIC].gnd = read_2;
-err:
- if (ret)
- dev_err(vadc->dev, "measure reference points failed\n");

return ret;
}
--
2.7.4