linux-kernel - Re: [PATCH] drivers/staging/greybus: fix max dup length for kstrndup

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Date:   Thu, 14 Dec 2017 10:49:45 +0000
From:   Rui Miguel Silva <rmfrfs@...il.com>
To:     Ma Shimiao <mashimiao.fnst@...fujitsu.com>
Cc:     linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org,
        greybus-dev@...ts.linaro.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] drivers/staging/greybus: fix max dup length for kstrndup

Hi Ma,
Thanks for your patch.

Please make sure you use scripts/get_maintainer.pl so that your patches
goes to the right lists and people. I CC's them now. ;)


On Tue 12 Dec 2017 at 09:25, Ma Shimiao wrote:
> If source string longer than max, kstrndup will alloc max+1 space.
> So, we should make sure the result will not over limit.

I think we are good here. kstrndup alloc memory for us the max+1, and
in fact we want to have the 32 chars plus the \0 set by kstrndup.

So, I think the code as is now is ok.

---
Cheers,
	Rui

>
> Signed-off-by: Ma Shimiao <mashimiao.fnst@...fujitsu.com>
> ---
>  drivers/staging/greybus/light.c        |  9 ++++++---
>  drivers/staging/greybus/power_supply.c | 10 ++++++----
>  2 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
> index 010ae1e9c7fb..c7ac2ead5a07 100644
> --- a/drivers/staging/greybus/light.c
> +++ b/drivers/staging/greybus/light.c
> @@ -965,10 +965,12 @@ static int gb_lights_channel_config(struct gb_light *light,
>  	channel->mode = le32_to_cpu(conf.mode);
>  	channel->flags = le32_to_cpu(conf.flags);
>  	channel->color = le32_to_cpu(conf.color);
> -	channel->color_name = kstrndup(conf.color_name, NAMES_MAX, GFP_KERNEL);
> +	channel->color_name = kstrndup(conf.color_name,
> +				       NAMES_MAX - 1, GFP_KERNEL);
>  	if (!channel->color_name)
>  		return -ENOMEM;
> -	channel->mode_name = kstrndup(conf.mode_name, NAMES_MAX, GFP_KERNEL);
> +	channel->mode_name = kstrndup(conf.mode_name,
> +				      NAMES_MAX - 1, GFP_KERNEL);
>  	if (!channel->mode_name)
>  		return -ENOMEM;
>  
> @@ -1027,7 +1029,8 @@ static int gb_lights_light_config(struct gb_lights *glights, u8 id)
>  		return -EINVAL;
>  
>  	light->channels_count = conf.channel_count;
> -	light->name = kstrndup(conf.name, NAMES_MAX, GFP_KERNEL);
> +	light->name = kstrndup(conf.name,
> +			       NAMES_MAX - 1, GFP_KERNEL);
>  
>  	light->channels = kcalloc(light->channels_count,
>  				  sizeof(struct gb_channel), GFP_KERNEL);
> diff --git a/drivers/staging/greybus/power_supply.c b/drivers/staging/greybus/power_supply.c
> index 0529e5628c24..7bc76633866b 100644
> --- a/drivers/staging/greybus/power_supply.c
> +++ b/drivers/staging/greybus/power_supply.c
> @@ -487,14 +487,16 @@ static int gb_power_supply_description_get(struct gb_power_supply *gbpsy)
>  	if (ret < 0)
>  		return ret;
>  
> -	gbpsy->manufacturer = kstrndup(resp.manufacturer, PROP_MAX, GFP_KERNEL);
> +	gbpsy->manufacturer = kstrndup(resp.manufacturer,
> +				       PROP_MAX - 1, GFP_KERNEL);
>  	if (!gbpsy->manufacturer)
>  		return -ENOMEM;
> -	gbpsy->model_name = kstrndup(resp.model, PROP_MAX, GFP_KERNEL);
> +	gbpsy->model_name = kstrndup(resp.model,
> +				     PROP_MAX - 1, GFP_KERNEL);
>  	if (!gbpsy->model_name)
>  		return -ENOMEM;
> -	gbpsy->serial_number = kstrndup(resp.serial_number, PROP_MAX,
> -				       GFP_KERNEL);
> +	gbpsy->serial_number = kstrndup(resp.serial_number,
> +					PROP_MAX - 1, GFP_KERNEL);
>  	if (!gbpsy->serial_number)
>  		return -ENOMEM;