Issue #13019: Fix potential reference leaks in bytearray.extend().

Patch by Suman Saha.

Misc/NEWS

@@ -9,6 +9,9 @@ What's New in Python 2.7.4
 Core and Builtins
 -----------------
 
+- Issue #13019: Fix potential reference leaks in bytearray.extend().  Patch
+  by Suman Saha.
+
 - Issue #14378: Fix compiling ast.ImportFrom nodes with a "__future__" string as
   the module name that was not interned.
 

Objects/bytearrayobject.c

@@ -2296,8 +2296,10 @@ bytearray_extend(PyByteArrayObject *self, PyObject *arg)
     }
 
     bytearray_obj = PyByteArray_FromStringAndSize(NULL, buf_size);
-    if (bytearray_obj == NULL)
+    if (bytearray_obj == NULL) {
+        Py_DECREF(it);
         return NULL;
+    }
     buf = PyByteArray_AS_STRING(bytearray_obj);
 
     while ((item = PyIter_Next(it)) != NULL) {
@@ -2330,8 +2332,10 @@ bytearray_extend(PyByteArrayObject *self, PyObject *arg)
         return NULL;
     }
 
-    if (bytearray_setslice(self, Py_SIZE(self), Py_SIZE(self), bytearray_obj) == -1)
+    if (bytearray_setslice(self, Py_SIZE(self), Py_SIZE(self), bytearray_obj) == -1) {
+        Py_DECREF(bytearray_obj);
         return NULL;
+    }
     Py_DECREF(bytearray_obj);
 
     Py_RETURN_NONE;