Issue #16628: Fix a memory leak in ctypes.resize().

pitrou · pitrou · commit 12f33df4a271 · 2012-12-08T11:07:16.000+01:00
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -104,6 +104,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #16628: Fix a memory leak in ctypes.resize().
+
 - Issue #13120: Allow to call pdb.set_trace() from thread.
   Patch by Ilya Sandler.
 
diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
@@ -2446,7 +2446,7 @@ PyCData_clear(CDataObject *self)
     assert(dict); /* Cannot be NULL for CDataObject instances */
     Py_CLEAR(self->b_objects);
     if ((self->b_needsfree)
-        && ((size_t)dict->size > sizeof(self->b_value)))
+        && _CDataObject_HasExternalBuffer(self))
         PyMem_Free(self->b_ptr);
     self->b_ptr = NULL;
     Py_CLEAR(self->b_base);
diff --git a/Modules/_ctypes/callproc.c b/Modules/_ctypes/callproc.c
@@ -1658,7 +1658,7 @@ resize(PyObject *self, PyObject *args)
         obj->b_size = size;
         goto done;
     }
-    if (obj->b_size <= sizeof(obj->b_value)) {
+    if (!_CDataObject_HasExternalBuffer(obj)) {
         /* We are currently using the objects default buffer, but it
            isn't large enough any more. */
         void *ptr = PyMem_Malloc(size);
diff --git a/Modules/_ctypes/ctypes.h b/Modules/_ctypes/ctypes.h
@@ -116,6 +116,7 @@ extern int PyObject_stginfo(PyObject *self, Py_ssize_t *psize, Py_ssize_t *palig
 extern PyTypeObject PyCData_Type;
 #define CDataObject_CheckExact(v)       ((v)->ob_type == &PyCData_Type)
 #define CDataObject_Check(v)            PyObject_TypeCheck(v, &PyCData_Type)
+#define _CDataObject_HasExternalBuffer(v)  ((v)->b_ptr != (char *)&(v)->b_value)
 
 extern PyTypeObject PyCSimpleType_Type;
 #define PyCSimpleTypeObject_CheckExact(v)       ((v)->ob_type == &PyCSimpleType_Type)

Original file line number	Diff line number	Diff line change
`@@ -1658,7 +1658,7 @@ resize(PyObject self, PyObject args)`
`1658`	`1658`	`obj->b_size = size;`
`1659`	`1659`	`goto done;`
`1660`	`1660`	`}`
`1661`		`- if (obj->b_size <= sizeof(obj->b_value)) {`
	`1661`	`+ if (!_CDataObject_HasExternalBuffer(obj)) {`
`1662`	`1662`	`/* We are currently using the objects default buffer, but it`
`1663`	`1663`	`isn't large enough any more. */`
`1664`	`1664`	`void *ptr = PyMem_Malloc(size);`