staging: vt6656: Don't leak memory in drivers/staging/vt6656/ioctl.c::private_ioctl()

If copy_to_user() fails in the WLAN_CMD_GET_NODE_LIST case of the
switch in drivers/staging/vt6656/ioctl.c::private_ioctl() we'll leak
the memory allocated to 'pNodeList'. Fix that by kfree'ing the memory
in the failure case.
Also remove a pointless cast (to type 'PSNodeList') of a kmalloc()
return value - kmalloc() returns a void pointer that is implicitly
converted, so there is no need for an explicit cast.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6656/ioctl.c

@@ -565,7 +565,7 @@ int private_ioctl(PSDevice pDevice, struct ifreq *rq)
 			result = -ENOMEM;
 			break;
 		}
-		pNodeList = (PSNodeList)kmalloc(sizeof(SNodeList) + (sNodeList.uItem * sizeof(SNodeItem)), (int)GFP_ATOMIC);
+		pNodeList = kmalloc(sizeof(SNodeList) + (sNodeList.uItem * sizeof(SNodeItem)), (int)GFP_ATOMIC);
 		if (pNodeList == NULL) {
 			result = -ENOMEM;
 			break;
@@ -601,6 +601,7 @@ int private_ioctl(PSDevice pDevice, struct ifreq *rq)
 			}
 		}
 		if (copy_to_user(pReq->data, pNodeList, sizeof(SNodeList) + (sNodeList.uItem * sizeof(SNodeItem)))) {
+			kfree(pNodeList);
 			result = -EFAULT;
 			break;
 		}