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SubjectRe: [PATCH v4] mfd: tps6105x: Fix possible NULL pointer access.
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@fastwel.ru>
> ---
> 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 │ Open source software for ARM SoCs
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