gpio: rockchip: avoid division by zero

[PATCH v2] gpio: rockchip: avoid division by zero

Posted by Ye Zhang 1 year, 5 months ago

If the clk_get_rate return '0', it will happen division by zero.

Fixes: 3bcbd1a85b68 ("gpio/rockchip: support next version gpio controller")
Signed-off-by: Ye Zhang <ye.zhang@rock-chips.com>
---
 drivers/gpio/gpio-rockchip.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpio/gpio-rockchip.c b/drivers/gpio/gpio-rockchip.c
index 0bd339813110..712258224eb3 100644
--- a/drivers/gpio/gpio-rockchip.c
+++ b/drivers/gpio/gpio-rockchip.c
@@ -207,6 +207,8 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
 	if (bank->gpio_type == GPIO_TYPE_V2 && !IS_ERR(bank->db_clk)) {
 		div_debounce_support = true;
 		freq = clk_get_rate(bank->db_clk);
+		if (!freq)
+			return -EINVAL;
 		max_debounce = (GENMASK(23, 0) + 1) * 2 * 1000000 / freq;
 		if (debounce > max_debounce)
 			return -EINVAL;
-- 
2.34.1

Re: [PATCH v2] gpio: rockchip: avoid division by zero

Posted by Andy Shevchenko 1 year, 5 months ago

On Fri, Aug 23, 2024 at 11:43:04AM +0800, Ye Zhang wrote:
> If the clk_get_rate return '0', it will happen division by zero.

At the abstraction level this is good to avoid 0 division and return an error,
but...

>  		freq = clk_get_rate(bank->db_clk);
> +		if (!freq)
> +			return -EINVAL;

...do you this the absence of debounce here is a fatal error?
(Yes, I see it's a fatal when it's bigger than maximum.)

>  		max_debounce = (GENMASK(23, 0) + 1) * 2 * 1000000 / freq;
>  		if (debounce > max_debounce)
>  			return -EINVAL;

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] gpio: rockchip: avoid division by zero

Posted by Heiko Stübner 1 year, 5 months ago

Am Freitag, 23. August 2024, 05:43:04 CEST schrieb Ye Zhang:
> If the clk_get_rate return '0', it will happen division by zero.
> 
> Fixes: 3bcbd1a85b68 ("gpio/rockchip: support next version gpio controller")
> Signed-off-by: Ye Zhang <ye.zhang@rock-chips.com>

Reviewed-by: Heiko Stuebner <heiko@sntech.de>

> ---
>  drivers/gpio/gpio-rockchip.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpio/gpio-rockchip.c b/drivers/gpio/gpio-rockchip.c
> index 0bd339813110..712258224eb3 100644
> --- a/drivers/gpio/gpio-rockchip.c
> +++ b/drivers/gpio/gpio-rockchip.c
> @@ -207,6 +207,8 @@ static int rockchip_gpio_set_debounce(struct gpio_chip *gc,
>  	if (bank->gpio_type == GPIO_TYPE_V2 && !IS_ERR(bank->db_clk)) {
>  		div_debounce_support = true;
>  		freq = clk_get_rate(bank->db_clk);
> +		if (!freq)
> +			return -EINVAL;
>  		max_debounce = (GENMASK(23, 0) + 1) * 2 * 1000000 / freq;
>  		if (debounce > max_debounce)
>  			return -EINVAL;
>