linux-kernel - Re: [PATCH 01/18] Input: joydev - use memdup_user() to duplicate memory from user-space

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Message-ID: <20151002182133.GN8437@dtor-ws>
Date:	Fri, 2 Oct 2015 11:21:33 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Javier Martinez Canillas <javier@....samsung.com>
Cc:	linux-kernel@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: [PATCH 01/18] Input: joydev - use memdup_user() to duplicate
 memory from user-space

On Fri, Oct 02, 2015 at 03:40:12PM +0200, Javier Martinez Canillas wrote:
> The memdup_user() helper function can be used to duplicate a memory region
> from user-space to kernel-space. There is no need to open code the same
> logic using kmalloc() and copy_from_user() instead. This was found with
> make coccicheck that reported the following warning:
> 
> drivers/input/joydev.c:447:10-17: WARNING opportunity for memdup_user
> drivers/input/joydev.c:483:10-17: WARNING opportunity for memdup_user
> 
> Signed-off-by: Javier Martinez Canillas <javier@....samsung.com>

Applied, thank you.

> ---
> 
>  drivers/input/joydev.c | 18 ++++++------------
>  1 file changed, 6 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/input/joydev.c b/drivers/input/joydev.c
> index 6cb5a3e5f9a1..e3dcd4abae18 100644
> --- a/drivers/input/joydev.c
> +++ b/drivers/input/joydev.c
> @@ -444,12 +444,9 @@ static int joydev_handle_JSIOCSAXMAP(struct joydev *joydev,
>  	len = min(len, sizeof(joydev->abspam));
>  
>  	/* Validate the map. */
> -	abspam = kmalloc(len, GFP_KERNEL);
> -	if (!abspam)
> -		return -ENOMEM;
> -
> -	if (copy_from_user(abspam, argp, len)) {
> -		retval = -EFAULT;
> +	abspam = memdup_user(argp, len);
> +	if (IS_ERR(abspam)) {
> +		retval = PTR_ERR(abspam);
>  		goto out;
>  	}
>  
> @@ -480,12 +477,9 @@ static int joydev_handle_JSIOCSBTNMAP(struct joydev *joydev,
>  	len = min(len, sizeof(joydev->keypam));
>  
>  	/* Validate the map. */
> -	keypam = kmalloc(len, GFP_KERNEL);
> -	if (!keypam)
> -		return -ENOMEM;
> -
> -	if (copy_from_user(keypam, argp, len)) {
> -		retval = -EFAULT;
> +	keypam = memdup_user(argp, len);
> +	if (IS_ERR(keypam)) {
> +		retval = PTR_ERR(keypam);
>  		goto out;
>  	}
>  
> -- 
> 2.4.3
> 

-- 
Dmitry
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