Re: [PATCH V2 1/2] serial: mctrl_gpio: Check for NULL pointer

[Yegor Yefremov]

On Sun, Oct 6, 2019 at 6:33 PM Adam Ford <aford173@xxxxxxxxx> wrote:
>
> When using mctrl_gpio_to_gpiod, it dereferences gpios into a single
> requested GPIO.  This dereferencing can break if gpios is NULL,
> so this patch adds a NULL check before dereferencing it.  If
> gpios is NULL, this function will also return NULL.
>
> Signed-off-by: Adam Ford <aford173@xxxxxxxxx>

Reviewed-by: Yegor Yefremov <yegorslists@xxxxxxxxxxxxxx>

> ---
> V2:  This patch is new to the V2 of this series, so patch 2/2 can
>      work without risking a NULL dereference
> diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
> index d9074303c88e..fb4781292d40 100644
> --- a/drivers/tty/serial/serial_mctrl_gpio.c
> +++ b/drivers/tty/serial/serial_mctrl_gpio.c
> @@ -66,6 +66,9 @@ EXPORT_SYMBOL_GPL(mctrl_gpio_set);
>  struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
>                                       enum mctrl_gpio_idx gidx)
>  {
> +       if (gpios == NULL)
> +               return NULL;
> +
>         return gpios->gpio[gidx];
>  }
>  EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
> --
> 2.17.1
>