Python bindings: fix use-after-free on sub-geometries of a feature's geometry (#15355)

* Python bindings: fix use-after-free on sub-geometries after their parent is freed

* autotest: test sub-geometries after their parent is freed

Author: alonfaraj

autotest/ogr/ogr_basic_test.py

@@ -1236,6 +1236,37 @@ def test_geom_use_after_feature_delete_2(arg_type):
         geom.ExportToWkt()
 
 
+def test_subgeom_use_after_feature_delete():
+
+    feat = ogr.Feature(ogr.FeatureDefn())
+    feat.SetGeometry(ogr.CreateGeometryFromWkt("MULTIPOLYGON (((0 0,0 1,1 1,0 0)))"))
+    poly = feat.GetGeometryRef().GetGeometryRef(0)
+    ring = poly.GetGeometryRef(0)
+
+    del feat
+
+    with pytest.raises(Exception):
+        poly.ExportToWkt()
+
+    with pytest.raises(Exception):
+        ring.GetPointCount()
+
+
+def test_subgeom_use_after_geom_destroy():
+
+    geom = ogr.CreateGeometryFromWkt("MULTIPOLYGON (((0 0,0 1,1 1,0 0)))")
+    poly = geom.GetGeometryRef(0)
+    ring = poly.GetGeometryRef(0)
+
+    geom.Destroy()
+
+    with pytest.raises(Exception):
+        poly.ExportToWkt()
+
+    with pytest.raises(Exception):
+        ring.GetPointCount()
+
+
 def test_geom_use_after_transfer_to_feature_1(tmp_vsimem):
 
     ds = ogr.GetDriverByName("ESRI Shapefile").CreateDataSource(tmp_vsimem / "test.shp")

swig/include/python/ogr_python.i

@@ -857,6 +857,7 @@ def _WarnIfUserHasNotSpecifiedIfUsingExceptions():
     def _invalidate_geom_refs(self):
         if hasattr(self, '_geom_references'):
             for geom in self._geom_references:
+                geom._invalidate_geom_refs()
                 geom.this = None
 
 %}
@@ -994,9 +995,13 @@ def _WarnIfUserHasNotSpecifiedIfUsingExceptions():
 %extend OGRGeometryShadow {
 %pythoncode %{
   def Destroy(self):
+    self._invalidate_geom_refs()
     self.__swig_destroy__(self)
     self.thisown = 0
 
+  _add_geom_ref = Feature._add_geom_ref
+  _invalidate_geom_refs = Feature._invalidate_geom_refs
+
   def __str__(self):
     return self.ExportToIsoWkt()
 
@@ -1025,6 +1030,7 @@ def _WarnIfUserHasNotSpecifiedIfUsingExceptions():
 %feature("pythonappend") GetGeometryRef %{
     if val is not None:
         val._parent_geom = self
+        self._add_geom_ref(val)
 %}
 
 }