From 8c458e50d168d088219e214d7752428fe1cbea08 Mon Sep 17 00:00:00 2001
From: ***** <721466+soodoku@users.noreply.github.com>
Date: Sun, 26 Jul 2026 21:15:41 -0700
Subject: [PATCH] Tolerate a missing _cloudpickle_submodules key in
 _function_setstate

_function_setstate pops "_cloudpickle_submodules" from the slotstate without
a default, so a payload that does not carry that key raises an opaque
KeyError from inside pickle.loads rather than a normal unpickling failure.

Before c6f8cd4 the code guarded this:

    if '_cloudpickle_submodules' in state:
        state.pop('_cloudpickle_submodules')

That commit consolidated the module and the surviving version pops
unconditionally. Restore the tolerance by passing a default. Valid
cloudpickle payloads always set the key, so this is a no-op for them.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 CHANGES.md                 |  5 +++++
 cloudpickle/cloudpickle.py |  6 ++++--
 tests/cloudpickle_test.py  | 14 ++++++++++++++
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index a6b0b443..01c5b996 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,11 @@ In development
 - Make pickling of functions depending on globals in notebook more
   deterministic. ([PR#560](https://github.com/cloudpipe/cloudpickle/pull/560))
 
+- Tolerate a missing `_cloudpickle_submodules` key when restoring the state of
+  a dynamic function, so that a malformed payload no longer crashes with an
+  opaque `KeyError`.
+  ([issue#593](https://github.com/cloudpipe/cloudpickle/issues/593))
+
 3.1.2
 =====
 
diff --git a/cloudpickle/cloudpickle.py b/cloudpickle/cloudpickle.py
index 963a8259..ae042006 100644
--- a/cloudpickle/cloudpickle.py
+++ b/cloudpickle/cloudpickle.py
@@ -1152,8 +1152,10 @@ def _function_setstate(obj, state):
     # the pickled function to work correctly at unpickling time. Now that these
     # submodules are depickled (hence imported), they can be removed from the
     # object's state (the object state only served as a reference holder to
-    # these submodules)
-    slotstate.pop("_cloudpickle_submodules")
+    # these submodules). Tolerate its absence: valid cloudpickle payloads always
+    # set this key, but a malformed one need not, and popping it unguarded turns
+    # that into an opaque KeyError.
+    slotstate.pop("_cloudpickle_submodules", None)
 
     obj.__globals__.update(obj_globals)
     obj.__globals__["__builtins__"] = __builtins__
diff --git a/tests/cloudpickle_test.py b/tests/cloudpickle_test.py
index e2097d1c..0d17d7d0 100644
--- a/tests/cloudpickle_test.py
+++ b/tests/cloudpickle_test.py
@@ -48,6 +48,7 @@
 from cloudpickle.cloudpickle import _make_empty_cell
 from cloudpickle.cloudpickle import _extract_class_dict, _whichmodule
 from cloudpickle.cloudpickle import _lookup_module_and_qualname
+from cloudpickle.cloudpickle import _function_setstate
 
 from .testutils import subprocess_worker
 from .testutils import subprocess_pickle_echo
@@ -3180,5 +3181,18 @@ def test_module_level_pickler():
     assert cloudpickle.Pickler is cloudpickle.CloudPickler
 
 
+def test_function_setstate_without_submodules_key():
+    # #593: a payload whose slotstate lacks "_cloudpickle_submodules" must not
+    # crash with an opaque KeyError. Valid cloudpickle payloads always carry
+    # that key, but malformed ones need not, and the guard that used to allow
+    # for its absence was dropped when the module was consolidated.
+    def f(x):
+        return x
+
+    _function_setstate(f, ({}, {"__globals__": {}, "__closure__": None}))
+
+    assert f(1) == 1
+
+
 if __name__ == "__main__":
     unittest.main()