[3.7] bpo-9263: _PyObject_Dump() detects freed memory (GH-10061) (GH-10662)

* bpo-9263: _PyObject_Dump() detects freed memory (GH-10061)

_PyObject_Dump() now uses an heuristic to check if the object memory
has been freed: log "<freed object>" in that case.

The heuristic rely on the debug hooks on Python memory allocators
which fills the memory with DEADBYTE (0xDB) when memory is
deallocated. Use PYTHONMALLOC=debug to always enable these debug
hooks.

(cherry picked from commit 82af0b63b07aa8d92b50098e382b458143cfc677)

* bpo-9263: Fix _PyObject_Dump() for freed object (#10661)

If _PyObject_Dump() detects that the object is freed, don't try to
dump it (exit immediately).

Enhance also _PyObject_IsFreed(): it now detects if the pointer
itself looks like freed memory.

(cherry picked from commit 2cf5d32fd9e61488e8b0be55a2e92a752ba8b06b)

1 files changed, 1 insertions, 0 deletions

diff --git a/Include/object.h b/Include/object.h
index c772deaf57..bcf78afe6b 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -521,6 +521,7 @@ struct _Py_Identifier;
 PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int);
 PyAPI_FUNC(void) _Py_BreakPoint(void);
 PyAPI_FUNC(void) _PyObject_Dump(PyObject *);
+PyAPI_FUNC(int) _PyObject_IsFreed(PyObject *);
 #endif
 PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *);
 PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *);