[PATCH] can: c_can: Use platform id data when OF data is absent

[PATCH] can: c_can: Use platform id data when OF data is absent

[Pengpeng Hou]

The platform driver keeps controller metadata in both the OF match table
and the platform id table.  Probe reads the metadata with
device_get_match_data(), which does not fall back to platform id-table
driver_data.

When the device is matched through the platform id table, drvdata can
therefore be NULL before it is dereferenced for msg_obj_num and the
controller type.  Fall back to platform_get_device_id() when firmware
match data is not available.

Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
 drivers/net/can/c_can/c_can_platform.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
index 19c86b94a40e..564c9e5b4c2c 100644
--- a/drivers/net/can/c_can/c_can_platform.c
+++ b/drivers/net/can/c_can/c_can_platform.c
@@ -263,9 +263,17 @@ static int c_can_plat_probe(struct platform_device *pdev)
 	int irq;
 	struct clk *clk;
 	const struct c_can_driver_data *drvdata;
+	const struct platform_device_id *id;
 	struct device_node *np = pdev->dev.of_node;
 
 	drvdata = device_get_match_data(&pdev->dev);
+	if (!drvdata) {
+		id = platform_get_device_id(pdev);
+		if (!id)
+			return -ENODEV;
+
+		drvdata = (const struct c_can_driver_data *)id->driver_data;
+	}
 
 	/* get the appropriate clk */
 	clk = devm_clk_get(&pdev->dev, NULL);
-- 
2.50.1 (Apple Git-155)

Re: [PATCH] can: c_can: Use platform id data when OF data is absent

[Vincent Mailhol]

On 24/06/2026 at 07:49, Pengpeng Hou wrote:
> The platform driver keeps controller metadata in both the OF match table
> and the platform id table.  Probe reads the metadata with
> device_get_match_data(), which does not fall back to platform id-table
> driver_data.
> 
> When the device is matched through the platform id table, drvdata can
> therefore be NULL before it is dereferenced for msg_obj_num and the
> controller type.  Fall back to platform_get_device_id() when firmware
> match data is not available.

So, you are telling me that this patch fixes a NULL pointer
dereference? In that case, it needs to be backported. Please add a
Fixes: tag.

Fixes: 5e6c3454b405 ("net: can: Use device_get_match_data()")

> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
> ---
>  drivers/net/can/c_can/c_can_platform.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
> index 19c86b94a40e..564c9e5b4c2c 100644
> --- a/drivers/net/can/c_can/c_can_platform.c
> +++ b/drivers/net/can/c_can/c_can_platform.c
> @@ -263,9 +263,17 @@ static int c_can_plat_probe(struct platform_device *pdev)
>  	int irq;
>  	struct clk *clk;
>  	const struct c_can_driver_data *drvdata;
> +	const struct platform_device_id *id;
>  	struct device_node *np = pdev->dev.of_node;
>  
>  	drvdata = device_get_match_data(&pdev->dev);
> +	if (!drvdata) {
> +		id = platform_get_device_id(pdev);
> +		if (!id)
> +			return -ENODEV;
> +
> +		drvdata = (const struct c_can_driver_data *)id->driver_data;
> +	}

Reduce the visibility of id:

	if (!drvdata) {
		const struct platform_device_id *id;

		id = platform_get_device_id(pdev);
		if (!id)
			return -ENODEV;

		drvdata = (const struct c_can_driver_data *)id->driver_data;
	}

>  
>  	/* get the appropriate clk */
>  	clk = devm_clk_get(&pdev->dev, NULL);

With the Fixes: tag added and above nitpick addressed:

Reviewed-by: Vincent Mailhol <mailhol@kernel.org>


Yours sincerely,
Vincent Mailhol

Re: [PATCH] can: c_can: Use platform id data when OF data is absent

[Vincent Mailhol]

On 24/06/2026 at 11:53, Vincent Mailhol wrote:
> On 24/06/2026 at 07:49, Pengpeng Hou wrote:
>> The platform driver keeps controller metadata in both the OF match table
>> and the platform id table.  Probe reads the metadata with
>> device_get_match_data(), which does not fall back to platform id-table
>> driver_data.
>>
>> When the device is matched through the platform id table, drvdata can
>> therefore be NULL before it is dereferenced for msg_obj_num and the
>> controller type.  Fall back to platform_get_device_id() when firmware
>> match data is not available.
> 
> So, you are telling me that this patch fixes a NULL pointer
> dereference? In that case, it needs to be backported. Please add a
> Fixes: tag.

Also, were you able to trigger that NULL pointer dereference?

> Fixes: 5e6c3454b405 ("net: can: Use device_get_match_data()")
> 
>> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
>> ---
>>  drivers/net/can/c_can/c_can_platform.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
>> index 19c86b94a40e..564c9e5b4c2c 100644
>> --- a/drivers/net/can/c_can/c_can_platform.c
>> +++ b/drivers/net/can/c_can/c_can_platform.c
>> @@ -263,9 +263,17 @@ static int c_can_plat_probe(struct platform_device *pdev)
>>  	int irq;
>>  	struct clk *clk;
>>  	const struct c_can_driver_data *drvdata;
>> +	const struct platform_device_id *id;
>>  	struct device_node *np = pdev->dev.of_node;
>>  
>>  	drvdata = device_get_match_data(&pdev->dev);
>> +	if (!drvdata) {
>> +		id = platform_get_device_id(pdev);
>> +		if (!id)
>> +			return -ENODEV;
>> +
>> +		drvdata = (const struct c_can_driver_data *)id->driver_data;
>> +	}
> 
> Reduce the visibility of id:
> 
> 	if (!drvdata) {
> 		const struct platform_device_id *id;
> 
> 		id = platform_get_device_id(pdev);
> 		if (!id)
> 			return -ENODEV;
> 
> 		drvdata = (const struct c_can_driver_data *)id->driver_data;
> 	}
> 
>>  
>>  	/* get the appropriate clk */
>>  	clk = devm_clk_get(&pdev->dev, NULL);
> 
> With the Fixes: tag added and above nitpick addressed:
> 
> Reviewed-by: Vincent Mailhol <mailhol@kernel.org>


Yours sincerely,
Vincent Mailhol

[PATCH v2] can: c_can: Use platform id data when OF data is absent

[Pengpeng Hou]

The platform driver keeps controller metadata in both the OF match table
and the platform id table. Probe reads the metadata with
device_get_match_data(), which does not fall back to platform id-table
driver_data.

When the device is matched through the platform id table, drvdata can
therefore be NULL before it is dereferenced for msg_obj_num and the
controller type. Fall back to platform_get_device_id() when firmware
match data is not available.

Fixes: 5e6c3454b405 ("net: can: Use device_get_match_data()")
Cc: stable@vger.kernel.org
Reviewed-by: Vincent Mailhol <mailhol@kernel.org>
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
Changes in v2:
- Add the Fixes tag requested by Vincent.
- Scope the platform id variable inside the fallback block.
- Carry Vincent's Reviewed-by for the requested v2 shape.

 drivers/net/can/c_can/c_can_platform.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
index 19c86b94a40e..8a0c88839d24 100644
--- a/drivers/net/can/c_can/c_can_platform.c
+++ b/drivers/net/can/c_can/c_can_platform.c
@@ -267,6 +267,14 @@ static int c_can_plat_probe(struct platform_device *pdev)
 	struct device_node *np = pdev->dev.of_node;
 
 	drvdata = device_get_match_data(&pdev->dev);
+	if (!drvdata) {
+		const struct platform_device_id *id;
+
+		id = platform_get_device_id(pdev);
+		if (!id)
+			return -ENODEV;
+		drvdata = (const struct c_can_driver_data *)id->driver_data;
+	}
 
 	/* get the appropriate clk */
 	clk = devm_clk_get(&pdev->dev, NULL);
-- 
2.50.1

Re: [PATCH v2] can: c_can: Use platform id data when OF data is absent

[Uwe Kleine-König]

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Hello,

On Thu, Jun 25, 2026 at 01:41:52PM +0800, Pengpeng Hou wrote:
> The platform driver keeps controller metadata in both the OF match table
> and the platform id table. Probe reads the metadata with
> device_get_match_data(), which does not fall back to platform id-table
> driver_data.
> 
> When the device is matched through the platform id table, drvdata can
> therefore be NULL before it is dereferenced for msg_obj_num and the
> controller type. Fall back to platform_get_device_id() when firmware
> match data is not available.
> 
> Fixes: 5e6c3454b405 ("net: can: Use device_get_match_data()")
> Cc: stable@vger.kernel.org
> Reviewed-by: Vincent Mailhol <mailhol@kernel.org>
> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
> ---
> Changes in v2:
> - Add the Fixes tag requested by Vincent.
> - Scope the platform id variable inside the fallback block.
> - Carry Vincent's Reviewed-by for the requested v2 shape.
> 
>  drivers/net/can/c_can/c_can_platform.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
> index 19c86b94a40e..8a0c88839d24 100644
> --- a/drivers/net/can/c_can/c_can_platform.c
> +++ b/drivers/net/can/c_can/c_can_platform.c
> @@ -267,6 +267,14 @@ static int c_can_plat_probe(struct platform_device *pdev)
>  	struct device_node *np = pdev->dev.of_node;
>  
>  	drvdata = device_get_match_data(&pdev->dev);
> +	if (!drvdata) {
> +		const struct platform_device_id *id;
> +
> +		id = platform_get_device_id(pdev);
> +		if (!id)
> +			return -ENODEV;
> +		drvdata = (const struct c_can_driver_data *)id->driver_data;
> +	}

Given that there are no devices probed via the platform_driver's
id_table (or my grep misses it:

	$ git grep -E '"(c_can_platform|c_can|d_can)"'
	drivers/net/can/c_can/c_can_platform.c:         .name = "c_can",
	drivers/net/can/c_can/c_can_platform.c:         .name = "d_can",
)

just do:

	if (!drvdata)
		return -ENODEV;

and drop c_can_id_table[].

An error message would be nice, but the other error exits don't have one
either.

Unless I missed something a backport to stable isn't needed then,
either.

Best regards
Uwe

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