Issue #12149: Update the method cache after a type's dictionnary gets
cleared by the garbage collector. This fixes a segfault when an instance
and its type get caught in a reference cycle, and the instance's
deallocator calls one of the methods on the type (e.g. when subclassing
IOBase).
Diagnosis and patch by Davide Rizzo.
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index cfd4583..39fda2b 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -611,7 +611,24 @@
self.assertEqual(rawio.read(2), b"")
class CIOTest(IOTest):
- pass
+
+ def test_IOBase_finalize(self):
+ # Issue #12149: segmentation fault on _PyIOBase_finalize when both a
+ # class which inherits IOBase and an object of this class are caught
+ # in a reference cycle and close() is already in the method cache.
+ class MyIO(self.IOBase):
+ def close(self):
+ pass
+
+ # create an instance to populate the method cache
+ MyIO()
+ obj = MyIO()
+ obj.obj = obj
+ wr = weakref.ref(obj)
+ del MyIO
+ del obj
+ support.gc_collect()
+ self.assertTrue(wr() is None, wr)
class PyIOTest(IOTest):
pass
diff --git a/Misc/ACKS b/Misc/ACKS
index 45b4042..625317d 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -736,6 +736,7 @@
Nicholas Riley
Jean-Claude Rimbault
Juan M. Bello Rivas
+Davide Rizzo
Anthony Roach
Mark Roberts
Jim Robinson
diff --git a/Misc/NEWS b/Misc/NEWS
index 9a46b72..3df8e95 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,12 @@
Core and Builtins
-----------------
+- Issue #12149: Update the method cache after a type's dictionnary gets
+ cleared by the garbage collector. This fixes a segfault when an instance
+ and its type get caught in a reference cycle, and the instance's
+ deallocator calls one of the methods on the type (e.g. when subclassing
+ IOBase). Diagnosis and patch by Davide Rizzo.
+
- Issue #9611, #9015: FileIO.read() clamps the length to INT_MAX on Windows.
- When a generator yields, do not retain the caller's exception state on the
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 3c724fd..97ccf01 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -967,6 +967,8 @@
assert(basedealloc);
basedealloc(self);
+ PyType_Modified(type);
+
/* Can't reference self beyond this point */
Py_DECREF(type);