gh-92930: _pickle.c: Acquire strong references before calling save() (GH-92931)

(cherry picked from commit 4c496f1f115a7910d4606b4de233d14874c77bfa)

Co-authored-by: Dennis Sweeney <36520290+sweeneyde@users.noreply.github.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
index d0ea7d0..21419e1 100644
--- a/Lib/test/pickletester.py
+++ b/Lib/test/pickletester.py
@@ -3035,6 +3035,67 @@ class AbstractPickleTests:
         # 2-D, non-contiguous
         check_array(arr[::2])
 
+    def test_evil_class_mutating_dict(self):
+        # https://github.com/python/cpython/issues/92930
+        from random import getrandbits
+
+        global Bad
+        class Bad:
+            def __eq__(self, other):
+                return ENABLED
+            def __hash__(self):
+                return 42
+            def __reduce__(self):
+                if getrandbits(6) == 0:
+                    collection.clear()
+                return (Bad, ())
+
+        for proto in protocols:
+            for _ in range(20):
+                ENABLED = False
+                collection = {Bad(): Bad() for _ in range(20)}
+                for bad in collection:
+                    bad.bad = bad
+                    bad.collection = collection
+                ENABLED = True
+                try:
+                    data = self.dumps(collection, proto)
+                    self.loads(data)
+                except RuntimeError as e:
+                    expected = "changed size during iteration"
+                    self.assertIn(expected, str(e))
+
+    def test_evil_pickler_mutating_collection(self):
+        # https://github.com/python/cpython/issues/92930
+        if not hasattr(self, "pickler"):
+            raise self.skipTest(f"{type(self)} has no associated pickler type")
+
+        global Clearer
+        class Clearer:
+            pass
+
+        def check(collection):
+            class EvilPickler(self.pickler):
+                def persistent_id(self, obj):
+                    if isinstance(obj, Clearer):
+                        collection.clear()
+                    return None
+            pickler = EvilPickler(io.BytesIO(), proto)
+            try:
+                pickler.dump(collection)
+            except RuntimeError as e:
+                expected = "changed size during iteration"
+                self.assertIn(expected, str(e))
+
+        for proto in protocols:
+            check([Clearer()])
+            check([Clearer(), Clearer()])
+            check({Clearer()})
+            check({Clearer(), Clearer()})
+            check({Clearer(): 1})
+            check({Clearer(): 1, Clearer(): 2})
+            check({1: Clearer(), 2: Clearer()})
+
 
 class BigmemPickleTests: