Re: [PATCH] firmware: arm_scmi: Fix to check return value of of_match_device

[Steven Price <steven.price@arm.com>]

On 18/03/2019 23:04, Aditya Pakki wrote:
> of_match_device can return NULL if no matching device is found. This patch
> checks and returns -ENODEV in such a scenario.
> 
> Signed-off-by: Aditya Pakki <pakki001@umn.edu>
> ---
>  drivers/firmware/arm_scmi/driver.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index 8f952f2f1a29..0e0330b44b7b 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -799,6 +799,8 @@ static int scmi_probe(struct platform_device *pdev)
>  	}
>  
>  	desc = of_match_device(scmi_of_match, dev)->data;
> +	if (!desc)
> +		return -ENODEV;

If of_match_device() returns NULL, we've already dereferenced it due to
the "->data" access.

This would be better changed to be a call to of_device_get_match_data()
which handles the NULL return gracefully.

Steve