CCS/CC2640R2F: What's the difference between ICall_allocMsg and ICall_malloc and the associated free functions

Hello.The important thing is that only ICall_freeMsg is used to free memory allocated with ICall_allocMsg and only ICall_free is used to free memory allocated with ICall_malloc

The ICall alloc / free MSG functions are just helper functions for the normal ICall alloc / free functions. The source code for both is available in icall.c:

void *ICall_allocMsg(size_t size)
{
  ICall_MsgHdr *hdr =
      (ICall_MsgHdr *) ICall_heapMalloc(sizeof(ICall_MsgHdr) + size);

  if (!hdr)
  {
    return NULL;
  }
  hdr->len = size;
  hdr->next = NULL;
  hdr->dest_id = ICALL_UNDEF_DEST_ID;
  return ((void *) (hdr + 1));

}

void *ICall_malloc(uint_least16_t size)
{
  return (ICall_heapMalloc(size));
}

As you can see, ICall_allocMsg adds a message header to the allocation. You could of course accomplish the same thing by adding the header size to your alloc size yourself and then using ICall_malloc. 

The problem arises if, for example, you use ICall_FreeMsg to free memory that was allocated with ICall_Malloc.  In this case, since you freeing size + header when really only size was allocated, you will end up freeing memory that is still being used. Similarly you will run into problems in the reverse scenario.