void free_circularly_linked_list(struct node *head) {
      struct node *tmp = head->next;
      while (1) {
        if (tmp == head) {
          /* Has to be a separate case since even assigning
           * a dangling pointer is UB I believe? */
          free(tmp);
          break;
        } else {
          struct node *next = tmp->next;
          free(tmp);
          tmp = next;
        }
      }
    }

Let's say head value is "10" and the memory at "10" is {..., next: "10"}

After the first iteration we will have:

Head: "10" Next: "10" Temp: "10"

With "10" pointing to freed memory. But why do we care? We are not dereferencing it, are we?

(I think I am missing something very obvious)