bpo-31764: Prevent a crash in sqlite3.Cursor.close() in case the Cursor object is uninitialized (#3958)

Author: orenmn

Lib/sqlite3/test/regression.py

@@ -190,6 +190,9 @@ def __init__(self, con):
  cur = Cursor(con)
  with self.assertRaises(sqlite.ProgrammingError):
  cur.execute("select 4+5").fetchall()
+ with self.assertRaisesRegex(sqlite.ProgrammingError,
+ r'^Base Cursor\.__init__ not called\.$'):
+ cur.close()
 
  def CheckStrSubclass(self):
  """

Misc/NEWS.d/next/Library/2017-10-11-22-18-04.bpo-31764.EMyIkK.rst

@@ -0,0 +1,2 @@
+Prevent a crash in ``sqlite3.Cursor.close()`` in case the ``Cursor`` object is
+uninitialized. Patch by Oren Milman.

Modules/_sqlite/cursor.c

@@ -889,6 +889,11 @@ PyObject* pysqlite_noop(pysqlite_Connection* self, PyObject* args)
 
 PyObject* pysqlite_cursor_close(pysqlite_Cursor* self, PyObject* args)
 {
+ if (!self->connection) {
+ PyErr_SetString(pysqlite_ProgrammingError,
+ "Base Cursor.__init__ not called.");
+ return NULL;
+ }
  if (!pysqlite_check_thread(self->connection) || !pysqlite_check_connection(self->connection)) {
  return NULL;
  }