gh-151763: Fix OOM-0014 crash in _interpchannels._channel_id

Lib/test/test__interpchannels.py

@@ -6,7 +6,9 @@
 import time
 import unittest
 
+from test import support
 from test.support import import_helper
+from test.support.script_helper import run_python_until_end
 
 _channels = import_helper.import_module('_interpchannels')
 from concurrent.interpreters import _crossinterp
@@ -308,6 +310,33 @@ def test_bad_kwargs(self):
         with self.assertRaises(ValueError):
             _channels._channel_id(10, send=False, recv=False)
 
+    @unittest.skipIf(support.Py_TRACE_REFS,
+                     '_testcapi.set_nomemory() is unreliable with Py_TRACE_REFS')
+    def test_oom_in_module_lookup(self):
+        import_helper.import_module('_testcapi')
+        code = dedent("""
+            import _interpchannels
+            import _testcapi
+            from test.support import SuppressCrashReport
+
+            seen = False
+            with SuppressCrashReport():
+                _testcapi.set_nomemory(0, 1)
+                try:
+                    _interpchannels._channel_id(0)
+                except MemoryError:
+                    seen = True
+                finally:
+                    _testcapi.remove_mem_hooks()
+            if not seen:
+                raise AssertionError("MemoryError not raised")
+            print("MemoryError")
+        """)
+        with support.SuppressCrashReport():
+            res, _ = run_python_until_end("-c", code)
+        self.assertEqual(res.rc, 0, res.err.decode("ascii", "replace"))
+        self.assertIn(b"MemoryError", res.out)
+
     def test_does_not_exist(self):
         cid = _channels.create(REPLACE)
         with self.assertRaises(_channels.ChannelNotFoundError):

Misc/NEWS.d/next/Library/2026-06-22-09-41-31.gh-issue-151763.OOM0014.rst

@@ -0,0 +1,3 @@
+Fix a crash in ``_interpchannels._channel_id()`` when memory allocation
+fails while looking up module state. The function now correctly propagates
+``MemoryError``.

Modules/_interpchannelsmodule.c

@@ -3484,6 +3484,9 @@ channelsmod__channel_id(PyObject *self, PyObject *args, PyObject *kwds)
     PyTypeObject *cls = state->ChannelIDType;
 
     PyObject *mod = get_module_from_owned_type(cls);
+    if (mod == NULL) {
+        return NULL;
+    }
     assert(mod == self);
     Py_DECREF(mod);