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

Yongzhi Liu
2022-05-21T03:36:08Z

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 <lyz_cs@pku.edu.cn>
---
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