linux-kernel - Re: [PATCH] leds: lm3697: Fix out-of-bound access

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Date:   Mon, 5 Oct 2020 18:48:09 +0200
From:   Alexander Dahl <post@...pocky.de>
To:     ultracoolguy@...anota.com
Cc:     Dan Murphy <dmurphy@...com>, Marek Behun <kabel@...ckhole.sk>,
        Pavel <pavel@....cz>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Linux Leds <linux-leds@...r.kernel.org>
Subject: Re: [PATCH] leds: lm3697: Fix out-of-bound access

Hei hei,

On Mon, Oct 05, 2020 at 05:35:38PM +0200, ultracoolguy@...anota.com wrote:
> Well, the major benefit I see is that it makes the driver slightly
> more readable. However I'm fine with whatever you guys decide.
> 
> I'll attach the patch with the struct renaming removed just in case.

Note: your patch, especially the commit message, still needs a
Signed-off-by line.  Please read [1] (again?) and resend.

Greets
Alex

[1] https://www.kernel.org/doc/html/latest/process/submitting-patches.html

> Oct 5, 2020, 14:41 by dmurphy@...com:
> 
> > Gabriel
> >
> > On 10/5/20 9:38 AM, ultracoolguy@...anota.com wrote:
> >
> >> I understand. So I should leave it like it was and do the rename in another patch?
> >>
> >
> > You should do the fix in one patch and leave the structure name alone.
> >
> > The structure naming if fine and has no benefit and actually will make it more difficult for others to backport future fixes.
> >
> > Unless Pavel finds benefit in accepting the structure rename.
> >
> > Dan
> >
> 

> >From ee004d26bb2f91491141aa06f5518cc411711ff0 Mon Sep 17 00:00:00 2001
> From: Ultracoolguy <ultracoolguy@...anota.com>
> Date: Fri, 2 Oct 2020 18:27:00 -0400
> Subject: [PATCH] leds:lm3697:Fix out-of-bound access
> 
> If both led banks aren't used in device tree,
> an out-of-bounds condition in lm3697_init occurs
> because of the for loop assuming that all the banks are used.
> Fix it by adding a variable that contains the number of used banks.
> ---
>  drivers/leds/leds-lm3697.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/leds/leds-lm3697.c b/drivers/leds/leds-lm3697.c
> index 024983088d59..bd53450050b2 100644
> --- a/drivers/leds/leds-lm3697.c
> +++ b/drivers/leds/leds-lm3697.c
> @@ -78,8 +78,9 @@ struct lm3697 {
>  	struct mutex lock;
>  
>  	int bank_cfg;
> +	int num_banks;
>  
> -	struct lm3697_led leds[];
> +	struct lm3697_led banks[];
>  };
>  
>  static const struct reg_default lm3697_reg_defs[] = {
> @@ -180,8 +181,8 @@ static int lm3697_init(struct lm3697 *priv)
>  	if (ret)
>  		dev_err(&priv->client->dev, "Cannot write OUTPUT config\n");
>  
> -	for (i = 0; i < LM3697_MAX_CONTROL_BANKS; i++) {
> -		led = &priv->leds[i];
> +	for (i = 0; i < priv->num_banks; i++) {
> +		led = &priv->banks[i];
>  		ret = ti_lmu_common_set_ramp(&led->lmu_data);
>  		if (ret)
>  			dev_err(&priv->client->dev, "Setting the ramp rate failed\n");
> @@ -228,7 +229,7 @@ static int lm3697_probe_dt(struct lm3697 *priv)
>  			goto child_out;
>  		}
>  
> -		led = &priv->leds[i];
> +		led = &priv->banks[i];
>  
>  		ret = ti_lmu_common_get_brt_res(&priv->client->dev,
>  						child, &led->lmu_data);
> @@ -307,16 +308,17 @@ static int lm3697_probe(struct i2c_client *client,
>  	int ret;
>  
>  	count = device_get_child_node_count(&client->dev);
> -	if (!count) {
> -		dev_err(&client->dev, "LEDs are not defined in device tree!");
> -		return -ENODEV;
> +	if (!count || count > LM3697_MAX_CONTROL_BANKS) {
> +		return -EINVAL;
>  	}
>  
> -	led = devm_kzalloc(&client->dev, struct_size(led, leds, count),
> +	led = devm_kzalloc(&client->dev, struct_size(led, banks, count),
>  			   GFP_KERNEL);
>  	if (!led)
>  		return -ENOMEM;
>  
> +	led->num_banks = count;
> +
>  	mutex_init(&led->lock);
>  	i2c_set_clientdata(client, led);
>  
> -- 
> 2.28.0
> 


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