[v1,4/4] thermal: tegra: fix coverity defect

Message ID 1541410354-19090-5-git-send-email-wni@nvidia.com
State New
Headers show
Series
  • Fixes for Tegra soctherm
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Commit Message

Wei Ni Nov. 5, 2018, 9:32 a.m.
Fix dereference dev before null check.

Signed-off-by: Wei Ni <wni@nvidia.com>
---
 drivers/thermal/tegra/soctherm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Thierry Reding Nov. 8, 2018, 12:37 p.m. | #1
On Mon, Nov 05, 2018 at 05:32:34PM +0800, Wei Ni wrote:
> Fix dereference dev before null check.
> 
> Signed-off-by: Wei Ni <wni@nvidia.com>
> ---
>  drivers/thermal/tegra/soctherm.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/tegra/soctherm.c b/drivers/thermal/tegra/soctherm.c
> index 3042837364e8..96527df91f2a 100644
> --- a/drivers/thermal/tegra/soctherm.c
> +++ b/drivers/thermal/tegra/soctherm.c
> @@ -397,7 +397,7 @@ static int throttrip_program(struct device *dev,
>  			     struct soctherm_throt_cfg *stc,
>  			     int trip_temp)
>  {
> -	struct tegra_soctherm *ts = dev_get_drvdata(dev);
> +	struct tegra_soctherm *ts;
>  	int temp, cpu_throt, gpu_throt;
>  	unsigned int throt;
>  	u32 r, reg_off;
> @@ -405,6 +405,8 @@ static int throttrip_program(struct device *dev,
>  	if (!sg || !stc || !stc->init)
>  		return -EINVAL;
>  
> +	ts = dev_get_drvdata(dev);

I think coverity is wrong. How is dev ever going to be NULL in this
case? We allocate all of these struct tegra_thermctl_zone structures in
tegra_soctherm_probe() and assign zone->dev = &pdev->dev, which can
never be NULL.

And even if it could, the code would've crashed earlier in
tegra_soctherm_probe() already.

Furthermore, I fail to see how your patch would fix the defect. None of
the checks in the conditional above actually check the dev value.

Thierry
Wei Ni Nov. 9, 2018, 6:44 a.m. | #2
On 8/11/2018 8:37 PM, Thierry Reding wrote:
> On Mon, Nov 05, 2018 at 05:32:34PM +0800, Wei Ni wrote:
>> Fix dereference dev before null check.
>>
>> Signed-off-by: Wei Ni <wni@nvidia.com>
>> ---
>>  drivers/thermal/tegra/soctherm.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/thermal/tegra/soctherm.c b/drivers/thermal/tegra/soctherm.c
>> index 3042837364e8..96527df91f2a 100644
>> --- a/drivers/thermal/tegra/soctherm.c
>> +++ b/drivers/thermal/tegra/soctherm.c
>> @@ -397,7 +397,7 @@ static int throttrip_program(struct device *dev,
>>  			     struct soctherm_throt_cfg *stc,
>>  			     int trip_temp)
>>  {
>> -	struct tegra_soctherm *ts = dev_get_drvdata(dev);
>> +	struct tegra_soctherm *ts;
>>  	int temp, cpu_throt, gpu_throt;
>>  	unsigned int throt;
>>  	u32 r, reg_off;
>> @@ -405,6 +405,8 @@ static int throttrip_program(struct device *dev,
>>  	if (!sg || !stc || !stc->init)
>>  		return -EINVAL;
>>  
>> +	ts = dev_get_drvdata(dev);
> 
> I think coverity is wrong. How is dev ever going to be NULL in this
> case? We allocate all of these struct tegra_thermctl_zone structures in
> tegra_soctherm_probe() and assign zone->dev = &pdev->dev, which can
> never be NULL.
> 
> And even if it could, the code would've crashed earlier in
> tegra_soctherm_probe() already.
> 
> Furthermore, I fail to see how your patch would fix the defect. None of
> the checks in the conditional above actually check the dev value.
> 
Yes, you are right, we doesn't need this change. The driver would not
pass null dev in any case.
And this driver already had a change "1fba81cc09bd thermal: tegra:
remove null check for dev pointer" which remove this "dev" checking.

Thank.
Wei.

> Thierry
>

Patch

diff --git a/drivers/thermal/tegra/soctherm.c b/drivers/thermal/tegra/soctherm.c
index 3042837364e8..96527df91f2a 100644
--- a/drivers/thermal/tegra/soctherm.c
+++ b/drivers/thermal/tegra/soctherm.c
@@ -397,7 +397,7 @@  static int throttrip_program(struct device *dev,
 			     struct soctherm_throt_cfg *stc,
 			     int trip_temp)
 {
-	struct tegra_soctherm *ts = dev_get_drvdata(dev);
+	struct tegra_soctherm *ts;
 	int temp, cpu_throt, gpu_throt;
 	unsigned int throt;
 	u32 r, reg_off;
@@ -405,6 +405,8 @@  static int throttrip_program(struct device *dev,
 	if (!sg || !stc || !stc->init)
 		return -EINVAL;
 
+	ts = dev_get_drvdata(dev);
+
 	temp = enforce_temp_range(dev, trip_temp) / ts->soc->thresh_grain;
 
 	/* Hardcode LIGHT on LEVEL1 and HEAVY on LEVEL2 */