linux-kernel - Re: [PATCH] platform/chrome: cros_ec_typec: Handle NULL EC pointer during probe.

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Date:   Wed, 29 Apr 2020 23:58:02 +0200
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Daniil Lunev <dlunev@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     Prashant Malani <pmalani@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH] platform/chrome: cros_ec_typec: Handle NULL EC pointer
 during probe.

Hi Daniil,

Thank you for the patch.

On 28/4/20 3:02, Daniil Lunev wrote:
> Missing EC in device hierarchy causes NULL pointer to be returned to the
> probe function which leads to NULL pointer dereference when trying to
> send a command to the EC. This can be the case if the device is missing
> or incorrectly configured in the firmware blob. Even if the situation

There is any production device with a buggy firmware outside? Or this is just
for defensive programming while developing the firmware? Which device is
affected for this issue?

Thanks,
 Enric

> occures, the driver shall not cause a kernel panic as the condition is
> not critical for the system functions.
> 
> Signed-off-by: Daniil Lunev <dlunev@...omium.org>
> ---
> 
>  drivers/platform/chrome/cros_ec_typec.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> index 874269c07073..30d99c930445 100644
> --- a/drivers/platform/chrome/cros_ec_typec.c
> +++ b/drivers/platform/chrome/cros_ec_typec.c
> @@ -301,6 +301,11 @@ static int cros_typec_probe(struct platform_device *pdev)
>  
>  	typec->dev = dev;
>  	typec->ec = dev_get_drvdata(pdev->dev.parent);
> +	if (!typec->ec) {
> +		dev_err(dev, "Failed to get Cros EC data\n");
> +		return -EINVAL;
> +	}
> +
>  	platform_set_drvdata(pdev, typec);
>  
>  	ret = cros_typec_get_cmd_version(typec);
>