Language: Python
Label: vulnerable
CWE: CWE-787 \u2014 Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.

Code:
def append_dyn_array(darray_node, elem_node):
    assert isinstance(darray_node.typ, DArrayT)

    assert darray_node.typ.count > 0, "jerk boy u r out"

    ret = ["seq"]
    with darray_node.cache_when_complex("darray") as (b1, darray_node):
        len_ = get_dyn_array_count(darray_node)
        with len_.cache_when_complex("old_darray_len") as (b2, len_):
            assertion = ["assert", ["lt", len_, darray_node.typ.count]]
            ret.append(IRnode.from_list(assertion, error_msg=f"{darray_node.typ} bounds check"))
            ret.append(STORE(darray_node, ["add", len_, 1]))
            # NOTE: typechecks elem_node
            # NOTE skip array bounds check bc we already asserted len two lines up
            ret.append(
                make_setter(get_element_ptr(darray_node, len_, array_bounds_check=False), elem_node)
            )
            return IRnode.from_list(b1.resolve(b2.resolve(ret)))