Fix escape via generators etc.

Yes - we need to do allow-lists not deny-lists... 2.0

Co-authored-by: decorator-factory <decorator-factory@protonmail.com>

Author: danthedeckie

Diff for: simpleeval.py

@@ -61,6 +61,7 @@
 - kurtmckee (Kurt McKee) Infrastructure updates
 - edgarrmondragon (Edgar Ramírez-Mondragón) Address Python 3.12+ deprecation warnings
 - cedk (Cédric Krier) <ced@b2ck.com> Allow running tests with Werror
+- decorator-factory <decorator-factory@protonmail.com> More security fixes
 
 -------------------------------------
 Basic Usage:
@@ -115,7 +116,16 @@
 MAX_SHIFT = 10000  # highest << or >> (lshift / rshift)
 MAX_SHIFT_BASE = int(sys.float_info.max)  # highest on left side of << or >>
 DISALLOW_PREFIXES = ["_", "func_"]
-DISALLOW_METHODS = ["format", "format_map", "mro"]
+DISALLOW_METHODS = [
+    "format",
+    "format_map",
+    "mro",
+    "tb_frame",
+    "gi_frame",
+    "ag_frame",
+    "cr_frame",
+    "exec",
+]
 
 # Disallow functions:
 # This, strictly speaking, is not necessary.  These /should/ never be accessable anyway,

Diff for: test_simpleeval.py

@@ -1230,6 +1230,17 @@ def test_functions_are_disallowed_in_expressions(self):
 
         simpleeval.DEFAULT_FUNCTIONS = DF.copy()
 
+    def test_breakout_via_generator(self):
+        # Thanks decorator-factory
+        class Foo:
+            def bar(self):
+                yield "Hello, world!"
+
+        evil = "foo.bar().gi_frame.f_globals['__builtins__'].exec('raise RuntimeError(\"Oh no\")')"
+
+        with self.assertRaises(FeatureNotAvailable):
+            simple_eval(evil, names={"foo": Foo()})
+
 
 @unittest.skipIf(platform.python_implementation() == "PyPy", "GC set_debug not available in PyPy")
 class TestReferenceCleanup(DRYTest):