[3.9] bpo-31746: Prevent segfaults when sqlite3.Connection is uninitialised (GH-27431)

Lib/sqlite3/test/dbapi.py

@@ -192,6 +192,27 @@ def CheckSameThreadErrorOnOldVersion(self):
  sqlite.connect(':memory:', check_same_thread=False)
  self.assertEqual(str(cm.exception), 'shared connections not available')
 
+
+class UninitialisedConnectionTests(unittest.TestCase):
+ def setUp(self):
+ self.cx = sqlite.Connection.__new__(sqlite.Connection)
+
+ def test_uninit_operations(self):
+ funcs = (
+ lambda: self.cx.isolation_level,
+ lambda: self.cx.total_changes,
+ lambda: self.cx.in_transaction,
+ lambda: self.cx.iterdump(),
+ lambda: self.cx.cursor(),
+ lambda: self.cx.close(),
+ )
+ for func in funcs:
+ with self.subTest(func=func):
+ self.assertRaisesRegex(sqlite.ProgrammingError,
+ "Base Connection.__init__ not called",
+ func)
+
+
 class CursorTests(unittest.TestCase):
  def setUp(self):
  self.cx = sqlite.connect(":memory:")
@@ -943,10 +964,11 @@ def suite():
  closed_con_suite = unittest.makeSuite(ClosedConTests, "Check")
  closed_cur_suite = unittest.makeSuite(ClosedCurTests, "Check")
  on_conflict_suite = unittest.makeSuite(SqliteOnConflictTests, "Check")
+ uninit_con_suite = unittest.makeSuite(UninitialisedConnectionTests)
  return unittest.TestSuite((
  module_suite, connection_suite, cursor_suite, thread_suite,
  constructor_suite, ext_suite, closed_con_suite, closed_cur_suite,
- on_conflict_suite,
+ on_conflict_suite, uninit_con_suite,
  ))
 
 def test():

Modules/_sqlite/connection.c

@@ -102,8 +102,6 @@ int pysqlite_connection_init(pysqlite_Connection* self, PyObject* args, PyObject
 
  database = PyBytes_AsString(database_obj);
 
- self->initialized = 1;
-
  self->begin_statement = NULL;
 
  Py_CLEAR(self->statement_cache);
@@ -149,7 +147,7 @@ int pysqlite_connection_init(pysqlite_Connection* self, PyObject* args, PyObject
  Py_INCREF(isolation_level);
  }
  Py_CLEAR(self->isolation_level);
- if (pysqlite_connection_set_isolation_level(self, isolation_level, NULL) < 0) {
+ if (pysqlite_connection_set_isolation_level(self, isolation_level, NULL) != 0) {
  Py_DECREF(isolation_level);
  return -1;
  }
@@ -208,6 +206,8 @@ int pysqlite_connection_init(pysqlite_Connection* self, PyObject* args, PyObject
  self->ProgrammingError = pysqlite_ProgrammingError;
  self->NotSupportedError = pysqlite_NotSupportedError;
 
+ self->initialized = 1;
+
  return 0;
 }
 
@@ -339,6 +339,12 @@ PyObject* pysqlite_connection_close(pysqlite_Connection* self, PyObject* args)
  return NULL;
  }
 
+ if (!self->initialized) {
+ PyErr_SetString(pysqlite_ProgrammingError,
+ "Base Connection.__init__ not called.");
+ return NULL;
+ }
+
  pysqlite_do_all_statements(self, ACTION_FINALIZE, 1);
 
  if (self->db) {
@@ -1143,6 +1149,9 @@ int pysqlite_check_thread(pysqlite_Connection* self)
 
 static PyObject* pysqlite_connection_get_isolation_level(pysqlite_Connection* self, void* unused)
 {
+ if (!pysqlite_check_connection(self)) {
+ return NULL;
+ }
  Py_INCREF(self->isolation_level);
  return self->isolation_level;
 }
@@ -1175,11 +1184,17 @@ pysqlite_connection_set_isolation_level(pysqlite_Connection* self, PyObject* iso
  return -1;
  }
  if (isolation_level == Py_None) {
- PyObject *res = pysqlite_connection_commit(self, NULL);
- if (!res) {
- return -1;
+ /* We might get called during connection init, so we cannot use
+ * pysqlite_connection_commit() here. */
+ if (self->db && !sqlite3_get_autocommit(self->db)) {
+ int rc;
+ Py_BEGIN_ALLOW_THREADS
+ rc = sqlite3_exec(self->db, "COMMIT", NULL, NULL, NULL);
+ Py_END_ALLOW_THREADS
+ if (rc != SQLITE_OK) {
+ return _pysqlite_seterror(self->db, NULL);
+ }
  }
- Py_DECREF(res);
 
  self->begin_statement = NULL;
  } else {