Writing behind the allocated memory

Code excerpt:
```
input = vmalloc(len);
...
input[len] = '\0';
```
From https://github.com/milesp20/intel_nuc_led/blob/6a3850eadff554053ca7d95e830a624b28c53670/nuc_led.c#L234

That should be:
```
input = vmalloc(len+1);
...
input[len] = '\0';
```


