linux-kernel - Re: [PATCH v3] mfd: tps6105x: Fix NULL pointer access.

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Message-ID: <20150923002306.GG9317@x1>
Date:	Wed, 23 Sep 2015 01:23:06 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Grigoryev Denis <grigoryev@...twel.ru>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Samuel Ortiz <sameo@...ux.intel.com>
Subject: Re: [PATCH v3] mfd: tps6105x: Fix NULL pointer access.

On Mon, 21 Sep 2015, Grigoryev Denis wrote:

> When tps6105x used in TPS6105X_MODE_SHUTDOWN mode the driver calls
> mfd_add_devices() with mfd_cell->name == NULL, that causes an ooops in
> platform_device_register() later.
> 
> This patch adds an mfd_cell for each possible mode thereby excluding
> .name assignment in runtime.
> 
> Signed-off-by: Denis Grigoryev <grigoryev@...twel.ru>
> ---
>  drivers/mfd/tps6105x.c |   61 +++++++++++++++++++++++++++---------------------
>  1 file changed, 35 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/mfd/tps6105x.c b/drivers/mfd/tps6105x.c
> index 5de95c2..6603fc8 100644
> --- a/drivers/mfd/tps6105x.c
> +++ b/drivers/mfd/tps6105x.c
> @@ -119,17 +119,25 @@ static int tps6105x_startup(struct tps6105x *tps6105x)
>  }
>  
>  /*
> - * MFD cells - we have one cell which is selected operation
> - * mode, and we always have a GPIO cell.
> + * MFD cells - we always have a GPIO cell and we have one cell
> + * which is selected operation mode.
>   */
>  static struct mfd_cell tps6105x_cells[] = {
> -	{
> -		/* name will be runtime assigned */
> -		.id = -1,
> +	[TPS6105X_MODE_SHUTDOWN]	= {
> +		.name			= "tps6105x-gpio",
> +		.id			= -1,
>  	},
> -	{
> -		.name = "tps6105x-gpio",
> -		.id = -1,
> +	[TPS6105X_MODE_TORCH]		= {
> +		.name			= "tps6105x-leds",
> +		.id			= -1,
> +	},
> +	[TPS6105X_MODE_TORCH_FLASH]	= {
> +		.name			= "tps6105x-flash",
> +		.id			= -1,
> +	},
> +	[TPS6105X_MODE_VOLTAGE]		= {
> +		.name			= "tps6105x-regulator",
> +		.id			= -1,

Why are these IDs all -1?

>  	},
>  };
>  
> @@ -157,38 +165,39 @@ static int tps6105x_probe(struct i2c_client *client,
>  		return ret;
>  	}
>  
> -	/* Remove warning texts when you implement new cell drivers */
> +	/* Set up and register the platform devices. */
> +	for (i = 0; i < ARRAY_SIZE(tps6105x_cells); i++) {
> +		/* One state holder for all drivers, this is simple */
> +		tps6105x_cells[i].platform_data = tps6105x;
> +		tps6105x_cells[i].pdata_size = sizeof(*tps6105x);
> +	}
> +
> +	ret = mfd_add_devices(&client->dev, -1, tps6105x_cells,
> +			      1, NULL, 0, NULL);
> +	if (ret)
> +		return ret;
> +
>  	switch (pdata->mode) {
>  	case TPS6105X_MODE_SHUTDOWN:
>  		dev_info(&client->dev,
>  			 "present, not used for anything, only GPIO\n");
>  		break;
>  	case TPS6105X_MODE_TORCH:
> -		tps6105x_cells[0].name = "tps6105x-leds";
> -		dev_warn(&client->dev,
> -			 "torch mode is unsupported\n");
> -		break;
>  	case TPS6105X_MODE_TORCH_FLASH:
> -		tps6105x_cells[0].name = "tps6105x-flash";
> -		dev_warn(&client->dev,
> -			 "flash mode is unsupported\n");
> -		break;
>  	case TPS6105X_MODE_VOLTAGE:
> -		tps6105x_cells[0].name ="tps6105x-regulator";
> +		ret = mfd_add_devices(&client->dev, -1,
> +				      &tps6105x_cells[pdata->mode],
> +				      1, NULL, 0, NULL);
>  		break;
>  	default:
> +		dev_warn(&client->dev, "invalid mode: %d\n", pdata->mode);
>  		break;
>  	}
>  
> -	/* Set up and register the platform devices. */
> -	for (i = 0; i < ARRAY_SIZE(tps6105x_cells); i++) {
> -		/* One state holder for all drivers, this is simple */
> -		tps6105x_cells[i].platform_data = tps6105x;
> -		tps6105x_cells[i].pdata_size = sizeof(*tps6105x);
> -	}
> +	if (ret)
> +		mfd_remove_devices(&client->dev);
>  
> -	return mfd_add_devices(&client->dev, 0, tps6105x_cells,
> -			       ARRAY_SIZE(tps6105x_cells), NULL, 0, NULL);
> +	return ret;
>  }
>  
>  static int tps6105x_remove(struct i2c_client *client)

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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