Merge pull request #10230 from dbaston/python-subgeom-parent-ref

Python bindings: Avoid crash when using orphaned subgeometry

autotest/ogr/ogr_geom.py

@@ -4519,3 +4519,13 @@ def test_ogr_geom_buffer_with_args():
 
     with pytest.raises(Exception, match="Unsupported buffer option"):
         geom.Buffer(1, {"QUALITY": "HIGH"})
+
+
+def test_ogr_subgeom_use_after_parent_free():
+
+    g = ogr.CreateGeometryFromWkt("POLYGON ((0 0, 1 0, 1 1, 0 0))")
+
+    exterior_ring = g.GetGeometryRef(0)
+    del g
+
+    assert exterior_ring.GetPointCount() > 0  # does not crash

swig/include/python/ogr_python.i

@@ -990,8 +990,13 @@ def _WarnIfUserHasNotSpecifiedIfUsingExceptions():
   def __iter__(self):
       for i in range(self.GetGeometryCount()):
           yield self.GetGeometryRef(i)
+%}
 
+%feature("pythonappend") GetGeometryRef %{
+    if val is not None:
+        val._parent_geom = self
 %}
+
 }