Re: [PATCH v4] mfd: tps6105x: Fix possible NULL pointer access.

[Lee Jones]

On Fri, 25 Sep 2015, Grigoryev Denis wrote:

> tps6105x driver provides two cells. One is for GPIO and another one is
> for selected mode depending on platform data. When tps6105x is used in
> GPIO-only mode, this driver calls mfd_add_devices() with mfd_cell
> .name == NULL. This value causes an oops in platform_device_register()
> later.
> 
> The following patch adds a mfd_cell for each possible mode thereby
> excluding .name assignment in runtime.
> 
> Signed-off-by: Denis Grigoryev <grigoryev@xxxxxxxxxx>
> ---
>  drivers/mfd/tps6105x.c |   72 +++++++++++++++++++++++++++++-------------------
>  1 file changed, 43 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/mfd/tps6105x.c b/drivers/mfd/tps6105x.c
> index 5de95c2..f34f19d 100644
> --- a/drivers/mfd/tps6105x.c
> +++ b/drivers/mfd/tps6105x.c
> @@ -119,27 +119,47 @@ 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,
> -	},
> -	{
> -		.name = "tps6105x-gpio",
> -		.id = -1,
> -	},
> +static struct mfd_cell tps6105x_dev_gpio = {
> +	.name = "tps6105x-gpio",
> +};
> +
> +static struct mfd_cell tps6105x_dev_leds = {
> +	.name = "tps6105x-leds",
> +};
> +
> +static struct mfd_cell tps6105x_dev_flash = {
> +	.name = "tps6105x-flash",
>  };
>  
> +static struct mfd_cell tps6105x_dev_regulator = {
> +	.name = "tps6105x-regulator",
> +};

Less confusing if you call these tps6105x_regulator_cell, etc.

> +static int tps6105x_add_device(struct tps6105x *tps6105x,
> +			       struct mfd_cell *cell)
> +{
> +	cell->platform_data = tps6105x;
> +	cell->pdata_size = sizeof(*tps6105x);
> +
> +	return mfd_add_devices(&tps6105x->client->dev,
> +			       PLATFORM_DEVID_AUTO, cell, 1, NULL, 0, NULL);
> +}
> +
>  static int tps6105x_probe(struct i2c_client *client,
>  			const struct i2c_device_id *id)
>  {
>  	struct tps6105x			*tps6105x;
>  	struct tps6105x_platform_data	*pdata;
>  	int ret;
> -	int i;
> +
> +	pdata = dev_get_platdata(&client->dev);
> +	if (pdata == NULL) {

if (!pdata)

> +		dev_err(&client->dev, "missing platform data\n");
> +		return -ENODEV;
> +	}
>  
>  	tps6105x = devm_kmalloc(&client->dev, sizeof(*tps6105x), GFP_KERNEL);
>  	if (!tps6105x)
> @@ -147,7 +167,6 @@ static int tps6105x_probe(struct i2c_client *client,
>  
>  	i2c_set_clientdata(client, tps6105x);
>  	tps6105x->client = client;
> -	pdata = dev_get_platdata(&client->dev);
>  	tps6105x->pdata = pdata;
>  	mutex_init(&tps6105x->lock);
>  
> @@ -157,38 +176,33 @@ static int tps6105x_probe(struct i2c_client *client,
>  		return ret;
>  	}
>  
> -	/* Remove warning texts when you implement new cell drivers */
> +	ret = tps6105x_add_device(tps6105x, &tps6105x_dev_gpio);
> +	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");
> +		ret = tps6105x_add_device(tps6105x, &tps6105x_dev_leds);
>  		break;
>  	case TPS6105X_MODE_TORCH_FLASH:
> -		tps6105x_cells[0].name = "tps6105x-flash";
> -		dev_warn(&client->dev,
> -			 "flash mode is unsupported\n");
> +		ret = tps6105x_add_device(tps6105x, &tps6105x_dev_flash);
>  		break;
>  	case TPS6105X_MODE_VOLTAGE:
> -		tps6105x_cells[0].name ="tps6105x-regulator";
> +		ret = tps6105x_add_device(tps6105x, &tps6105x_dev_regulator);
>  		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);

If ret is non-zero, then mfd_add_devices() failed and there are no
device to remove.

> -	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 â Open source software for ARM SoCs
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