LinuxTV Patchwork media: rcar-vin: fix a potential NULL pointer dereference

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Submitter Kangjie Lu
Date March 9, 2019, 7:05 a.m.
Message ID <20190309070527.2657-1-kjlu@umn.edu>
Download mbox | patch
Permalink /patch/54980/
State Changes Requested
Delegated to: Hans Verkuil
Headers show

Comments

Kangjie Lu - March 9, 2019, 7:05 a.m.
In case of_match_node cannot find a match, the fix returns
-EINVAL to avoid NULL pointer dereference.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
---
 drivers/media/platform/rcar-vin/rcar-core.c | 2 ++
 1 file changed, 2 insertions(+)
Niklas Söderlund - March 9, 2019, 11:02 a.m.
Hi Kangjie,

Thanks for your patch.

On 2019-03-09 01:05:27 -0600, Kangjie Lu wrote:
> In case of_match_node cannot find a match, the fix returns
> -EINVAL to avoid NULL pointer dereference.
> 
> Signed-off-by: Kangjie Lu <kjlu@umn.edu>
> ---
>  drivers/media/platform/rcar-vin/rcar-core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c
> index f0719ce24b97..a058e2023ca8 100644
> --- a/drivers/media/platform/rcar-vin/rcar-core.c
> +++ b/drivers/media/platform/rcar-vin/rcar-core.c
> @@ -266,6 +266,8 @@ static int rvin_group_init(struct rvin_group *group, struct rvin_dev *vin)
>  
>  	match = of_match_node(vin->dev->driver->of_match_table,
>  			      vin->dev->of_node);
> +	if (unlikely(!match))
> +		return -EINVAL;

I don't think this is needed. The driver depends on selects OF and if we 
get this far we it is because we had a match already. The reason to call 
of_match_node() here is simply to retrieve which of the possible 
compatible strings was matched.

Am I missing something? What scenario do you see where this can fail?

>  
>  	strscpy(mdev->driver_name, KBUILD_MODNAME, sizeof(mdev->driver_name));
>  	strscpy(mdev->model, match->compatible, sizeof(mdev->model));
> -- 
> 2.17.1
>
Hans Verkuil - March 28, 2019, 3:26 p.m.
On 3/9/19 12:02 PM, Niklas Söderlund wrote:
> Hi Kangjie,
> 
> Thanks for your patch.
> 
> On 2019-03-09 01:05:27 -0600, Kangjie Lu wrote:
>> In case of_match_node cannot find a match, the fix returns
>> -EINVAL to avoid NULL pointer dereference.
>>
>> Signed-off-by: Kangjie Lu <kjlu@umn.edu>
>> ---
>>  drivers/media/platform/rcar-vin/rcar-core.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c
>> index f0719ce24b97..a058e2023ca8 100644
>> --- a/drivers/media/platform/rcar-vin/rcar-core.c
>> +++ b/drivers/media/platform/rcar-vin/rcar-core.c
>> @@ -266,6 +266,8 @@ static int rvin_group_init(struct rvin_group *group, struct rvin_dev *vin)
>>  
>>  	match = of_match_node(vin->dev->driver->of_match_table,
>>  			      vin->dev->of_node);
>> +	if (unlikely(!match))
>> +		return -EINVAL;
> 
> I don't think this is needed. The driver depends on selects OF and if we 
> get this far we it is because we had a match already. The reason to call 
> of_match_node() here is simply to retrieve which of the possible 
> compatible strings was matched.
> 
> Am I missing something? What scenario do you see where this can fail?

And even if it can fail, then please drop the 'unlikely'.

Regards,

	Hans

> 
>>  
>>  	strscpy(mdev->driver_name, KBUILD_MODNAME, sizeof(mdev->driver_name));
>>  	strscpy(mdev->model, match->compatible, sizeof(mdev->model));
>> -- 
>> 2.17.1
>>
>

Patch

diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c
index f0719ce24b97..a058e2023ca8 100644
--- a/drivers/media/platform/rcar-vin/rcar-core.c
+++ b/drivers/media/platform/rcar-vin/rcar-core.c
@@ -266,6 +266,8 @@  static int rvin_group_init(struct rvin_group *group, struct rvin_dev *vin)
 
 	match = of_match_node(vin->dev->driver->of_match_table,
 			      vin->dev->of_node);
+	if (unlikely(!match))
+		return -EINVAL;
 
 	strscpy(mdev->driver_name, KBUILD_MODNAME, sizeof(mdev->driver_name));
 	strscpy(mdev->model, match->compatible, sizeof(mdev->model));

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