linux-kernel - RE: [PATCH] regmap: fix possible ZERO_SIZE

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Message-ID: <e0bb202c7b9c4384afa244f2f6165aa8@BY2PR0301MB0613.namprd03.prod.outlook.com>
Date:	Sun, 28 Sep 2014 09:25:06 +0000
From:	"Li.Xiubo@...escale.com" <Li.Xiubo@...escale.com>
To:	"broonie@...nel.org" <broonie@...nel.org>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] regmap: fix possible ZERO_SIZE_PTR pointer dereferencing
 error.

Hi Mark,


> Subject: [PATCH] regmap: fix possible ZERO_SIZE_PTR pointer dereferencing
> error.
> 
> Since we cannot make sure the 'val_count' will always be none zero
> here, and then if it equals to zero, the kmemdup() will return
> ZERO_SIZE_PTR, which equals to ((void *)16).
> 
> So this patch fix this with just doing the zero check before calling
> kmemdup().
> 
> Signed-off-by: Xiubo Li <Li.Xiubo@...escale.com>
> ---
>  drivers/base/regmap/regmap.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
> index 455a877..3d93e38 100644
> --- a/drivers/base/regmap/regmap.c
> +++ b/drivers/base/regmap/regmap.c
> @@ -1716,6 +1716,9 @@ out:
>  	} else {
>  		void *wval;
> 
> +		if (!val_count)
> +			return -EINVAL;
> +

Should it return zero as success or just return -EINVAL for error here ?

If it allow zero of val_count in regmap_bulk_write(..., val_count) could do
Nothing and just return zero as success at the beginning of it.

I will respin this patch if return zero is better ...

Thanks,

BRs
Xiubo

>  		wval = kmemdup(val, val_count * val_bytes, GFP_KERNEL);
>  		if (!wval) {
>  			dev_err(map->dev, "Error in memory allocation\n");
> --
> 2.1.0.27.g96db324

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