| Message ID | 1653238427-73587-1-git-send-email-lyz_cs@pku.edu.cn (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [v4] iio: vadc: Fix potential dereference of NULL pointer | expand |
On Sun, 22 May 2022 09:53:47 -0700 Yongzhi Liu <lyz_cs@pku.edu.cn> wrote: > The return value of vadc_get_channel() needs to be checked to > avoid use of NULL pointer. vadc_do_conversion() already provides > error prints in at least some of it's error paths. Thus it is > reasonable to add the null pointer check on prop and drop the > extra reporting in vadc_measure_ref_points(). > > Signed-off-by: Yongzhi Liu <lyz_cs@pku.edu.cn> Hi Biggest remaining thing is squashing ret = -ENODEV; return ret; into the shorter return -ENODEV; > --- > 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"); Probably makes more sense to have the error as "No 1.25V channel found\n"); It's not obvious to anyone getting this error what 'define' might mean without them looking at the code, so I'd rather we just said what had gone wrong rather offering incomplete advice. > + ret = -ENODEV; Don't bother assigning a variable just to return it in the next line. return -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"); "No 0.625V channel found\n" > + ret = -ENODEV; return -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"); "No VDD channel found\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"); "No GND channel found\n" > + ret = -ENODEV; > + return ret; return -ENODEV; > + } > 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; return -ENODEV; > } > > 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; Can't get here with anything other than ret == 0 so return 0; to make that explicit. > }
On Fri, 3 Jun 2022 16:02:22 +0100 Jonathan Cameron <jic23@kernel.org> wrote: > On Sun, 22 May 2022 09:53:47 -0700 > Yongzhi Liu <lyz_cs@pku.edu.cn> wrote: > > > The return value of vadc_get_channel() needs to be checked to > > avoid use of NULL pointer. vadc_do_conversion() already provides > > error prints in at least some of it's error paths. Thus it is > > reasonable to add the null pointer check on prop and drop the > > extra reporting in vadc_measure_ref_points(). > > > > Signed-off-by: Yongzhi Liu <lyz_cs@pku.edu.cn> > > Hi > > Biggest remaining thing is squashing > ret = -ENODEV; > return ret; > > into the shorter > return -ENODEV; > One additional process thing I didn't mention before now as this is a single patch. Generally for IIO at least, don't send new versions in reply to old threads. The threads can get very deep and confusing, so I'd much rather a new thread for each version. Thanks, Jonathan > > > --- > > 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"); > Probably makes more sense to have the error as > "No 1.25V channel found\n"); > > It's not obvious to anyone getting this error what 'define' might mean > without them looking at the code, so I'd rather we just said what had > gone wrong rather offering incomplete advice. > > > + ret = -ENODEV; > > Don't bother assigning a variable just to return it in the next line. > > return -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"); > "No 0.625V channel found\n" > > + ret = -ENODEV; > > return -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"); > > "No VDD channel found\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"); > > "No GND channel found\n" > > > + ret = -ENODEV; > > + return ret; > > return -ENODEV; > > > + } > > 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; > > return -ENODEV; > > > } > > > > 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; > > Can't get here with anything other than ret == 0 so > return 0; > to make that explicit. > > > > } >
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; }
The return value of vadc_get_channel() needs to be checked to avoid use of NULL pointer. vadc_do_conversion() already provides error prints in at least some of it's error paths. Thus it is reasonable to add the null pointer check on prop and drop the extra reporting in vadc_measure_ref_points(). 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(-)