Call stack error when creating binary tree with recursion

Question

The following code runs for a second and then a runtime error is caused by node->data = *data;

 Node *TreeCreate(int level, const char *data)
{
    Node *node = malloc(sizeof(node));

    if (node != NULL) {
    node->data = *data;
    }

    if (level != 0) {
        node->leftChild = TreeCreate(level - 1, data + 1);
        node->rightChild = TreeCreate(level - 1, data + (int)pow(2, level - 1));
    }
    return node;
}

Answer 1

Even if you reserved at least pow(2, level) characters for the string referenced by *data the next TreeCreate() call just fall off these boundaries:

TreeCreate(level, data) //--> 
    TreeCreate(level, data + 1) //--> ...
    TreeCreate(level, data + pow(2, level-1) // -->
           TreeCreate(level, data + pow(2, level-1) + 1) //-->  well still may fit to you string
           TreeCreate(level, data + pow(2, level-1) + pow(2, level-2) // --> may not fit 

For example, level = 4, size of the string pointed by data = 16, when walking down the TreeCreate() call tree for leftChild will result in: data + 4 + pow(2, 3) + pow(2, 2) + pow(2, 1) --> data + 18 (!!)