Segmentation fault occured since the commit ID 9e5c5497ab,
where we try to copy the pointer which was not even been allocated. Before, we were
copying the address of a NULL pointer and therefore no segmentation fault.
This commit fixes the segmentation fault by checking if the memory was allocated, i.e. should not be
in the case of CU (as it doesn't contain MAC/RLC layers).
Teodora
3f930551ff