diff mbox series

[1/7] Input: mtk-pmic-keys - check for NULL on of_match_device()

Message ID 20210428164219.1115537-2-mkorpershoek@baylibre.com (mailing list archive)
State New
Headers show
Series [1/7] Input: mtk-pmic-keys - check for NULL on of_match_device() | expand

Commit Message

Mattijs Korpershoek April 28, 2021, 4:42 p.m. UTC
mtk-pmic-keys being a child device of mt6397, it will always get probed
when mt6397_probe() is called.

This also happens when we have no device tree node matching
mediatek,mt6397-keys.

In that case, the mfd core warns us:

  [    0.352175] mtk-pmic-keys: Failed to locate of_node [id: -1]

Check return value from call to of_match_device()
in order to prevent a NULL pointer dereference.

In case of NULL print error message and return -ENODEV

Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
---
 drivers/input/keyboard/mtk-pmic-keys.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Dmitry Torokhov April 28, 2021, 7:52 p.m. UTC | #1
Hi Mattijs,

On Wed, Apr 28, 2021 at 06:42:13PM +0200, Mattijs Korpershoek wrote:
> mtk-pmic-keys being a child device of mt6397, it will always get probed
> when mt6397_probe() is called.
> 
> This also happens when we have no device tree node matching
> mediatek,mt6397-keys.

It sounds for me that creating a platform device instance in case where
we know need OF node, but do not have one, is wasteful. Can
mt6397-core.c and/or MFD core be adjusted to not do that.

> 
> In that case, the mfd core warns us:
> 
>   [    0.352175] mtk-pmic-keys: Failed to locate of_node [id: -1]
> 
> Check return value from call to of_match_device()
> in order to prevent a NULL pointer dereference.
> 
> In case of NULL print error message and return -ENODEV
> 
> Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
> ---
>  drivers/input/keyboard/mtk-pmic-keys.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/input/keyboard/mtk-pmic-keys.c b/drivers/input/keyboard/mtk-pmic-keys.c
> index 62391d6c7da6..12c449eed026 100644
> --- a/drivers/input/keyboard/mtk-pmic-keys.c
> +++ b/drivers/input/keyboard/mtk-pmic-keys.c
> @@ -247,6 +247,9 @@ static int mtk_pmic_keys_probe(struct platform_device *pdev)
>  	const struct of_device_id *of_id =
>  		of_match_device(of_mtk_pmic_keys_match_tbl, &pdev->dev);
>  
> +	if (!of_id)
> +		return -ENODEV;
> +

So if we make MFD/6396 core smarter we would not be needing this. I
guess there is still a possibility of someone stuffing "mtk-pmic-keys"
into "driver_override" attribute of a random platform device but I
wonder if we really need to take care of such scenarios...

>  	keys = devm_kzalloc(&pdev->dev, sizeof(*keys), GFP_KERNEL);
>  	if (!keys)
>  		return -ENOMEM;
> -- 
> 2.27.0
> 

Thanks.
Mattijs Korpershoek April 29, 2021, 6:48 a.m. UTC | #2
Hi Dmitry,

Dmitry Torokhov <dmitry.torokhov@gmail.com> writes:

> Hi Mattijs,
>
> On Wed, Apr 28, 2021 at 06:42:13PM +0200, Mattijs Korpershoek wrote:
>> mtk-pmic-keys being a child device of mt6397, it will always get probed
>> when mt6397_probe() is called.
>> 
>> This also happens when we have no device tree node matching
>> mediatek,mt6397-keys.
>
> It sounds for me that creating a platform device instance in case where
> we know need OF node, but do not have one, is wasteful. Can
> mt6397-core.c and/or MFD core be adjusted to not do that.

You are right. Maybe I can fix MFD core instead. I will look into it.

Thanks for your review.
>
>> 
>> In that case, the mfd core warns us:
>> 
>>   [    0.352175] mtk-pmic-keys: Failed to locate of_node [id: -1]
>> 
>> Check return value from call to of_match_device()
>> in order to prevent a NULL pointer dereference.
>> 
>> In case of NULL print error message and return -ENODEV
>> 
>> Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
>> ---
>>  drivers/input/keyboard/mtk-pmic-keys.c | 3 +++
>>  1 file changed, 3 insertions(+)
>> 
>> diff --git a/drivers/input/keyboard/mtk-pmic-keys.c b/drivers/input/keyboard/mtk-pmic-keys.c
>> index 62391d6c7da6..12c449eed026 100644
>> --- a/drivers/input/keyboard/mtk-pmic-keys.c
>> +++ b/drivers/input/keyboard/mtk-pmic-keys.c
>> @@ -247,6 +247,9 @@ static int mtk_pmic_keys_probe(struct platform_device *pdev)
>>  	const struct of_device_id *of_id =
>>  		of_match_device(of_mtk_pmic_keys_match_tbl, &pdev->dev);
>>  
>> +	if (!of_id)
>> +		return -ENODEV;
>> +
>
> So if we make MFD/6396 core smarter we would not be needing this. I
> guess there is still a possibility of someone stuffing "mtk-pmic-keys"
> into "driver_override" attribute of a random platform device but I
> wonder if we really need to take care of such scenarios...
>
>>  	keys = devm_kzalloc(&pdev->dev, sizeof(*keys), GFP_KERNEL);
>>  	if (!keys)
>>  		return -ENOMEM;
>> -- 
>> 2.27.0
>> 
>
> Thanks.
>
> -- 
> Dmitry
Mattijs Korpershoek April 29, 2021, 2:48 p.m. UTC | #3
Hi Dmitry,

Mattijs Korpershoek <mkorpershoek@baylibre.com> writes:

> Hi Dmitry,
>
> Dmitry Torokhov <dmitry.torokhov@gmail.com> writes:
>
>> Hi Mattijs,
>>
>> On Wed, Apr 28, 2021 at 06:42:13PM +0200, Mattijs Korpershoek wrote:
>>> mtk-pmic-keys being a child device of mt6397, it will always get probed
>>> when mt6397_probe() is called.
>>> 
>>> This also happens when we have no device tree node matching
>>> mediatek,mt6397-keys.
>>
>> It sounds for me that creating a platform device instance in case where
>> we know need OF node, but do not have one, is wasteful. Can
>> mt6397-core.c and/or MFD core be adjusted to not do that.
>
> You are right. Maybe I can fix MFD core instead. I will look into it.
>
> Thanks for your review.
>>
>>> 
>>> In that case, the mfd core warns us:
>>> 
>>>   [    0.352175] mtk-pmic-keys: Failed to locate of_node [id: -1]
>>> 
>>> Check return value from call to of_match_device()
>>> in order to prevent a NULL pointer dereference.
>>> 
>>> In case of NULL print error message and return -ENODEV
>>> 
>>> Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
>>> ---
>>>  drivers/input/keyboard/mtk-pmic-keys.c | 3 +++
>>>  1 file changed, 3 insertions(+)
>>> 
>>> diff --git a/drivers/input/keyboard/mtk-pmic-keys.c b/drivers/input/keyboard/mtk-pmic-keys.c
>>> index 62391d6c7da6..12c449eed026 100644
>>> --- a/drivers/input/keyboard/mtk-pmic-keys.c
>>> +++ b/drivers/input/keyboard/mtk-pmic-keys.c
>>> @@ -247,6 +247,9 @@ static int mtk_pmic_keys_probe(struct platform_device *pdev)
>>>  	const struct of_device_id *of_id =
>>>  		of_match_device(of_mtk_pmic_keys_match_tbl, &pdev->dev);
>>>  
>>> +	if (!of_id)
>>> +		return -ENODEV;
>>> +
>>
>> So if we make MFD/6396 core smarter we would not be needing this. I
>> guess there is still a possibility of someone stuffing "mtk-pmic-keys"
>> into "driver_override" attribute of a random platform device but I
>> wonder if we really need to take care of such scenarios...
It turns out it was possible to make 6397-core smarter.
I've submitted [1] to replace this patch.

Thanks again for your suggestion. Please let me know if I should add
your Suggested-by: in [1].

[1] https://patchwork.kernel.org/project/linux-mediatek/patch/20210429143811.2030717-1-mkorpershoek@baylibre.com/ instead
>>
>>>  	keys = devm_kzalloc(&pdev->dev, sizeof(*keys), GFP_KERNEL);
>>>  	if (!keys)
>>>  		return -ENOMEM;
>>> -- 
>>> 2.27.0
>>> 
>>
>> Thanks.
>>
>> -- 
>> Dmitry
diff mbox series

Patch

diff --git a/drivers/input/keyboard/mtk-pmic-keys.c b/drivers/input/keyboard/mtk-pmic-keys.c
index 62391d6c7da6..12c449eed026 100644
--- a/drivers/input/keyboard/mtk-pmic-keys.c
+++ b/drivers/input/keyboard/mtk-pmic-keys.c
@@ -247,6 +247,9 @@  static int mtk_pmic_keys_probe(struct platform_device *pdev)
 	const struct of_device_id *of_id =
 		of_match_device(of_mtk_pmic_keys_match_tbl, &pdev->dev);
 
+	if (!of_id)
+		return -ENODEV;
+
 	keys = devm_kzalloc(&pdev->dev, sizeof(*keys), GFP_KERNEL);
 	if (!keys)
 		return -ENOMEM;