bpo-36179: Fix ref leaks in _hashopenssl (GH-12158)

Fix two unlikely reference leaks in _hashopenssl. The leaks only occur in
out-of-memory cases. Thanks to Charalampos Stratakis.
Signed-off-by: Christian Heimes <christian@python.org>



https://bugs.python.org/issue36179

Misc/NEWS.d/next/Library/2019-03-04-10-42-46.bpo-36179.jEyuI-.rst

+Fix two unlikely reference leaks in _hashopenssl. The leaks only occur in
+out-of-memory cases.

Modules/_hashopenssl.c

@@ -109,17 +109,18 @@ newEVPobject(PyObject *name)
         return NULL;
     }
 
+    /* save the name for .name to return */
+    Py_INCREF(name);
+    retval->name = name;
+    retval->lock = NULL;
+
     retval->ctx = EVP_MD_CTX_new();
     if (retval->ctx == NULL) {
+        Py_DECREF(retval);
         PyErr_NoMemory();
         return NULL;
     }
 
-    /* save the name for .name to return */
-    Py_INCREF(name);
-    retval->name = name;
-    retval->lock = NULL;
-
     return retval;
 }
 
@@ -182,6 +183,7 @@ EVP_copy_impl(EVPobject *self)
         return NULL;
 
     if (!locked_EVP_MD_CTX_copy(newobj->ctx, self)) {
+        Py_DECREF(newobj);
         return _setException(PyExc_ValueError);
     }
     return (PyObject *)newobj;