linux-kernel - Re: [PATCH] staging: gdm72xx: add userspace data struct

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Message-ID: <566948F6.80904@wimdewith.com>
Date:	Thu, 10 Dec 2015 10:42:14 +0100
From:	Wim de With <nauxuron@...dewith.com>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	gregkh@...uxfoundation.org, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: gdm72xx: add userspace data struct

On 10-12-2015 10:37, Dan Carpenter wrote:
> On Thu, Dec 10, 2015 at 10:11:12AM +0100, Wim de With wrote:
>> @@ -482,8 +483,16 @@ static int gdm_wimax_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
>>  				/* NOTE: gdm_update_fsm should be called
>>  				 * before gdm_wimax_ioctl_set_data is called.
>>  				 */
>> -				gdm_update_fsm(dev,
>> -					       req->data.buf);
>> +				fsm_buf = kmalloc(sizeof(fsm_s), GFP_KERNEL);
>> +				if (!fsm_buf)
>> +					return -ENOMEM;
>> +				if (copy_from_user(fsm_buf, req->data.buf,
>> +						   sizeof(fsm_s))) {
>> +					kfree(fsm_buf);
>> +					return -EFAULT;
>> +				}
>> +				gdm_update_fsm(dev, fsm_buf);
>> +				kfree(fsm_buf);
> 
> 
> No.  This change is a bug.
> 
> regards,
> dan carpenter
> 

But what if I just keep it as:

	gdm_update_fsm(dev, req->data.buf)

Then it would just trust a __user pointer right?

Wim
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