iio: chemical: set val parameter only on success

[PATCH] iio: chemical: set val parameter only on success

Posted by trix@redhat.com 4 years, 6 months ago

From: Tom Rix <trix@redhat.com>

Clang static analysis reports this representative warning

sunrise_co2.c:410:9: warning: Assigned value is garbage or undefined
  *val = value;
       ^ ~~~~~

The ealier call to sunrise_read_word can fail without setting
value.  So defer setting val until we know the read was successful.

Fixes: c397894e24f1 ("iio: chemical: Add Senseair Sunrise 006-0-007 driver")
Signed-off-by: Tom Rix <trix@redhat.com>
---
 drivers/iio/chemical/sunrise_co2.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/chemical/sunrise_co2.c b/drivers/iio/chemical/sunrise_co2.c
index 233bd0f379c93..8440dc0c77cfe 100644
--- a/drivers/iio/chemical/sunrise_co2.c
+++ b/drivers/iio/chemical/sunrise_co2.c
@@ -407,24 +407,24 @@ static int sunrise_read_raw(struct iio_dev *iio_dev,
 			mutex_lock(&sunrise->lock);
 			ret = sunrise_read_word(sunrise, SUNRISE_CO2_FILTERED_COMP_REG,
 						&value);
-			*val = value;
 			mutex_unlock(&sunrise->lock);
 
 			if (ret)
 				return ret;
 
+			*val = value;
 			return IIO_VAL_INT;
 
 		case IIO_TEMP:
 			mutex_lock(&sunrise->lock);
 			ret = sunrise_read_word(sunrise, SUNRISE_CHIP_TEMPERATURE_REG,
 						&value);
-			*val = value;
 			mutex_unlock(&sunrise->lock);
 
 			if (ret)
 				return ret;
 
+			*val = value;
 			return IIO_VAL_INT;
 
 		default:
-- 
2.26.3

Re: [PATCH] iio: chemical: set val parameter only on success

Posted by Jonathan Cameron 4 years, 6 months ago

On Fri, 24 Dec 2021 07:08:33 -0800
trix@redhat.com wrote:

> From: Tom Rix <trix@redhat.com>
> 
> Clang static analysis reports this representative warning
> 
> sunrise_co2.c:410:9: warning: Assigned value is garbage or undefined
>   *val = value;
>        ^ ~~~~~
> 
> The ealier call to sunrise_read_word can fail without setting
> value.  So defer setting val until we know the read was successful.
> 
> Fixes: c397894e24f1 ("iio: chemical: Add Senseair Sunrise 006-0-007 driver")
> Signed-off-by: Tom Rix <trix@redhat.com>
Hi Tom,

This won't have any actual affect as if the read_raw callback returns a negative
error code we won't use the value.  However, good to clean it up so applied
to the togreg branch of iio.git.

Thanks,

Jonathan
> ---
>  drivers/iio/chemical/sunrise_co2.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/chemical/sunrise_co2.c b/drivers/iio/chemical/sunrise_co2.c
> index 233bd0f379c93..8440dc0c77cfe 100644
> --- a/drivers/iio/chemical/sunrise_co2.c
> +++ b/drivers/iio/chemical/sunrise_co2.c
> @@ -407,24 +407,24 @@ static int sunrise_read_raw(struct iio_dev *iio_dev,
>  			mutex_lock(&sunrise->lock);
>  			ret = sunrise_read_word(sunrise, SUNRISE_CO2_FILTERED_COMP_REG,
>  						&value);
> -			*val = value;
>  			mutex_unlock(&sunrise->lock);
>  
>  			if (ret)
>  				return ret;
>  
> +			*val = value;
>  			return IIO_VAL_INT;
>  
>  		case IIO_TEMP:
>  			mutex_lock(&sunrise->lock);
>  			ret = sunrise_read_word(sunrise, SUNRISE_CHIP_TEMPERATURE_REG,
>  						&value);
> -			*val = value;
>  			mutex_unlock(&sunrise->lock);
>  
>  			if (ret)
>  				return ret;
>  
> +			*val = value;
>  			return IIO_VAL_INT;
>  
>  		default: