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

1 files changed, 23 insertions, 7 deletions

diff --git a/Modules/_sqlite/connection.c b/Modules/_sqlite/connection.c
index a95b75a..dd332e5 100644
--- a/Modules/_sqlite/connection.c
+++ b/Modules/_sqlite/connection.c
@@ -111,8 +111,6 @@ pysqlite_connection_init_impl(pysqlite_Connection *self,
 
     const char *database = PyBytes_AsString(database_obj);
 
-    self->initialized = 1;
-
     self->begin_statement = NULL;
 
     Py_CLEAR(self->statement_cache);
@@ -147,7 +145,7 @@ pysqlite_connection_init_impl(pysqlite_Connection *self,
         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;
     }
@@ -195,6 +193,8 @@ pysqlite_connection_init_impl(pysqlite_Connection *self,
         return -1;
     }
 
+    self->initialized = 1;
+
     return 0;
 }
 
@@ -371,6 +371,13 @@ pysqlite_connection_close_impl(pysqlite_Connection *self)
         return NULL;
     }
 
+    if (!self->initialized) {
+        pysqlite_state *state = pysqlite_get_state(NULL);
+        PyErr_SetString(state->ProgrammingError,
+                        "Base Connection.__init__ not called.");
+        return NULL;
+    }
+
     pysqlite_do_all_statements(self, ACTION_FINALIZE, 1);
     connection_close(self);
 
@@ -1258,6 +1265,9 @@ 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;
+    }
     return Py_NewRef(self->isolation_level);
 }
 
@@ -1289,11 +1299,17 @@ 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);
+            }
         }
-        Py_DECREF(res);
 
         self->begin_statement = NULL;
     } else {