From fa106a685c1f199aca5be5c2d0277a14cc9057bd Mon Sep 17 00:00:00 2001
From: Pablo Galindo <Pablogsal@gmail.com>
Date: Sat, 5 Jun 2021 03:50:39 +0100
Subject: [PATCH] bpo-44304: Fix crash in the sqlite3 module when the GC clears
 Statement objects (GH-26545)

---
 Lib/sqlite3/test/userfunctions.py               | 17 +++++++++++++++++
 .../2021-06-05-02-34-57.bpo-44304._MAoPc.rst    |  2 ++
 Modules/_sqlite/statement.c                     | 11 ++++-------
 3 files changed, 23 insertions(+), 7 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2021-06-05-02-34-57.bpo-44304._MAoPc.rst

diff --git a/Lib/sqlite3/test/userfunctions.py b/Lib/sqlite3/test/userfunctions.py
index 6f57d1911b2..42908907249 100644
--- a/Lib/sqlite3/test/userfunctions.py
+++ b/Lib/sqlite3/test/userfunctions.py
@@ -23,6 +23,7 @@
 
 import unittest
 import unittest.mock
+import gc
 import sqlite3 as sqlite
 
 def func_returntext():
@@ -322,6 +323,22 @@ class FunctionTests(unittest.TestCase):
         with self.assertRaises(TypeError):
             self.con.create_function("deterministic", 0, int, True)
 
+    def test_function_destructor_via_gc(self):
+        # See bpo-44304: The destructor of the user function can
+        # crash if is called without the GIL from the gc functions
+        dest = sqlite.connect(':memory:')
+        def md5sum(t):
+            return
+
+        dest.create_function("md5", 1, md5sum)
+        x = dest("create table lang (name, first_appeared)")
+        del md5sum, dest
+
+        y = [x]
+        y.append(y)
+
+        del x,y
+        gc.collect()
 
 class AggregateTests(unittest.TestCase):
     def setUp(self):
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-06-05-02-34-57.bpo-44304._MAoPc.rst b/Misc/NEWS.d/next/Core and Builtins/2021-06-05-02-34-57.bpo-44304._MAoPc.rst
new file mode 100644
index 00000000000..89104e8e387
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-06-05-02-34-57.bpo-44304._MAoPc.rst	
@@ -0,0 +1,2 @@
+Fix a crash in the :mod:`sqlite3` module that happened when the garbage
+collector clears :class:`sqlite.Statement` objects. Patch by Pablo Galindo
diff --git a/Modules/_sqlite/statement.c b/Modules/_sqlite/statement.c
index c86645ad42b..c9dd8829453 100644
--- a/Modules/_sqlite/statement.c
+++ b/Modules/_sqlite/statement.c
@@ -403,6 +403,10 @@ stmt_dealloc(pysqlite_Statement *self)
     if (self->in_weakreflist != NULL) {
         PyObject_ClearWeakRefs((PyObject*)self);
     }
+    if (self->st) {
+        sqlite3_finalize(self->st);
+        self->st = 0;
+    }
     tp->tp_clear((PyObject *)self);
     tp->tp_free(self);
     Py_DECREF(tp);
@@ -411,13 +415,6 @@ stmt_dealloc(pysqlite_Statement *self)
 static int
 stmt_clear(pysqlite_Statement *self)
 {
-    if (self->st) {
-        Py_BEGIN_ALLOW_THREADS
-        sqlite3_finalize(self->st);
-        Py_END_ALLOW_THREADS
-        self->st = 0;
-    }
-
     Py_CLEAR(self->sql);
     return 0;
 }