[patch] Staging: vt6655-6: potential NULL dereference in hostap_disable_hostapd()

[Waskiewicz Jr, Peter P]

On Thu, 2013-11-07 at 10:55 +0300, Dan Carpenter wrote:
> We fixed this to use free_netdev() instead of kfree() but unfortunately
> free_netdev() doesn't accept NULL pointers.  Smatch complains about
> this, it's not something I discovered through testing.

Wouldn't a better approach be to change free_netdev() to allow it to
take NULL pointers?

-PJ

> Fixes: 3030d40b5036 ('staging: vt6655: use free_netdev instead of kfree')
> Fixes: 0a438d5b381e ('staging: vt6656: use free_netdev instead of kfree')
> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
> 
> diff --git a/drivers/staging/vt6655/hostap.c b/drivers/staging/vt6655/hostap.c
> index aab0012..ab8b2ba 100644
> --- a/drivers/staging/vt6655/hostap.c
> +++ b/drivers/staging/vt6655/hostap.c
> @@ -143,7 +143,8 @@ static int hostap_disable_hostapd(PSDevice pDevice, int rtnl_locked)
>  		DBG_PRT(MSG_LEVEL_DEBUG, KERN_INFO "%s: Netdevice %s unregistered\n",
>  			pDevice->dev->name, pDevice->apdev->name);
>  	}
> -	free_netdev(pDevice->apdev);
> +	if (pDevice->apdev)
> +		free_netdev(pDevice->apdev);
>  	pDevice->apdev = NULL;
>  	pDevice->bEnable8021x = false;
>  	pDevice->bEnableHostWEP = false;
> diff --git a/drivers/staging/vt6656/hostap.c b/drivers/staging/vt6656/hostap.c
> index ae1676d..67ba48b 100644
> --- a/drivers/staging/vt6656/hostap.c
> +++ b/drivers/staging/vt6656/hostap.c
> @@ -133,7 +133,8 @@ static int hostap_disable_hostapd(struct vnt_private *pDevice, int rtnl_locked)
>              DBG_PRT(MSG_LEVEL_DEBUG, KERN_INFO "%s: Netdevice %s unregistered\n",
>  		       pDevice->dev->name, pDevice->apdev->name);
>  	}
> -	free_netdev(pDevice->apdev);
> +	if (pDevice->apdev)
> +		free_netdev(pDevice->apdev);
>  	pDevice->apdev = NULL;
>      pDevice->bEnable8021x = false;
>      pDevice->bEnableHostWEP = false;