Fix: Prevent use of uninitialized memory when creating Bezier spline

When Constructing bezier splines from dna, the positions of the
left/right handles were set directly in the internal vectors, by
requesting a reference to them. The problem is that
BezierSpline::handle_positions_left() calls ensure_auto_handles()
before returning the reference. That function does some calculations on
uninitialized memory if the positions array is not yet filled.

Differential Revision: https://developer.blender.org/D13107

1 files changed, 14 insertions, 2 deletions

diff --git a/source/blender/blenkernel/BKE_spline.hh b/source/blender/blenkernel/BKE_spline.hh
index 8509b730709..55a4f6ffcfd 100644
--- a/source/blender/blenkernel/BKE_spline.hh
+++ b/source/blender/blenkernel/BKE_spline.hh
@@ -306,11 +306,23 @@ class BezierSpline final : public Spline {
   blender::Span<HandleType> handle_types_left() const;
   blender::MutableSpan<HandleType> handle_types_left();
   blender::Span<blender::float3> handle_positions_left() const;
-  blender::MutableSpan<blender::float3> handle_positions_left();
+  /**
+   * Get writable access to the hande position.
+   *
+   * \param write_only: pass true for an uninitialized spline, this prevents accessing
+   * uninitialized memory while autogenerating handles.
+   */
+  blender::MutableSpan<blender::float3> handle_positions_left(bool write_only = false);
   blender::Span<HandleType> handle_types_right() const;
   blender::MutableSpan<HandleType> handle_types_right();
   blender::Span<blender::float3> handle_positions_right() const;
-  blender::MutableSpan<blender::float3> handle_positions_right();
+  /**
+   * Get writable access to the hande position.
+   *
+   * \param write_only: pass true for an uninitialized spline, this prevents accessing
+   * uninitialized memory while autogenerating handles.
+   */
+  blender::MutableSpan<blender::float3> handle_positions_right(bool write_only = false);
   void ensure_auto_handles() const;
 
   void translate(const blender::float3 &translation) override;