Harden deferred instantiate dispatch on 1.3

Reject the two-argument iter callback overload while preserving ordinary iteration, and deny direct partial-call and property-getter dispatch before side effects can run.

Complements the coordinated #3412/#3413 policy backport.

hydra/_internal/instantiate/_instantiate2.py

@@ -69,6 +69,7 @@
     "concurrent.futures.process.ProcessPoolExecutor.map",
     "concurrent.futures.process.ProcessPoolExecutor.submit",
     "concurrent.futures.thread.ThreadPoolExecutor.submit",
+    "functools.partial.__call__",
     "functools.reduce",
     "itertools.accumulate",
     "itertools.groupby",
@@ -86,6 +87,7 @@
 }
 
 _CALLABLE_DESCRIPTOR_BINDING_TARGETS: Dict[type, str] = {
+    property: "builtins.property.__get__",
     types.ClassMethodDescriptorType: "types.ClassMethodDescriptorType.__get__",
     types.FunctionType: "types.FunctionType.__get__",
     types.MethodDescriptorType: "types.MethodDescriptorType.__get__",
@@ -484,6 +486,17 @@ def _authorize_target_invocation(
     allow_incomplete_partial: bool = False,
 ) -> None:
     target_name = _get_resolved_target_name_for_check(target)
+    if target_name == "builtins.iter" and len(args) == 2:
+        msg = dedent(
+            """\
+            Target 'builtins.iter' cannot use its two-argument callback form from
+            config because callback execution is deferred beyond instantiate's
+            target authorization. Use one-argument iter(iterable), or perform the
+            callback iteration in trusted Python code. This restriction cannot be
+            bypassed with HYDRA_INSTANTIATE_ALLOWLIST_OVERRIDE."""
+        )
+        raise InstantiationException(_with_full_key(msg, full_key))
+
     if target_name in _NON_CALLABLE_MOCK_TARGETS:
         unsafe_parameters = sorted(
             set(kwargs).difference(_NON_CALLABLE_MOCK_SAFE_PARAMETERS)

tests/instantiate/test_instantiate.py

@@ -1881,7 +1881,6 @@ def test_resolved_target_aliases_are_blocklisted(
     "target",
     [
         "builtins.filter",
-        "builtins.iter",
         "itertools.dropwhile",
         "itertools.filterfalse",
         "itertools.takewhile",
@@ -1891,6 +1890,66 @@ def test_non_result_lazy_callback_targets_are_not_blocklisted(target: str) -> No
     assert not _instantiate2._is_blocklisted_target(target)
 
 
+def test_one_argument_iter_target_is_allowed() -> None:
+    result = _instantiate2.instantiate(
+        {"_target_": "builtins.iter", "_args_": [[1, 2]]}
+    )
+
+    assert list(result) == [1, 2]
+
+
+def test_two_argument_iter_callback_cannot_be_allowlisted(monkeypatch: Any) -> None:
+    calls: List[str] = []
+
+    def callback() -> int:
+        calls.append("called")
+        return 1
+
+    monkeypatch.setenv("HYDRA_INSTANTIATE_ALLOWLIST_OVERRIDE", "builtins.iter")
+    cfg = {"_target_": "builtins.iter", "_args_": [callback, 2]}
+    with raises(InstantiationException, match="two-argument callback form"):
+        _instantiate2.instantiate(cfg)
+
+    assert calls == []
+
+
+def test_partial_call_target_cannot_be_allowlisted(monkeypatch: Any) -> None:
+    calls: List[str] = []
+
+    def callback() -> None:
+        calls.append("called")
+
+    target = "functools.partial.__call__"
+    monkeypatch.setenv("HYDRA_INSTANTIATE_ALLOWLIST_OVERRIDE", target)
+    cfg = {"_target_": target, "_args_": [partial(callback)]}
+    with raises(InstantiationException, match="cannot be authorized"):
+        _instantiate2.instantiate(cfg)
+
+    assert calls == []
+
+
+def test_property_get_target_cannot_be_allowlisted(monkeypatch: Any) -> None:
+    calls: List[str] = []
+
+    class Receiver:
+        pass
+
+    def getter(_: Receiver) -> int:
+        calls.append("called")
+        return 42
+
+    target = "builtins.property.__get__"
+    monkeypatch.setenv("HYDRA_INSTANTIATE_ALLOWLIST_OVERRIDE", target)
+    cfg = {
+        "_target_": target,
+        "_args_": [property(getter), Receiver(), Receiver],
+    }
+    with raises(InstantiationException, match="cannot be authorized"):
+        _instantiate2.instantiate(cfg)
+
+    assert calls == []
+
+
 def test_discovery_target_applies_blocklist_to_selected_path() -> None:
     cfg = {"_target_": "hydra.utils.get_method", "path": "builtins.eval"}
     with raises(InstantiationException, match="Target 'builtins.eval'.*blocklisted"):