From 06eeea8cb2782b90113148954bba5fdd8c54b5d1 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@freecad.org>
Date: Thu, 13 Feb 2025 12:07:00 +0100
Subject: [PATCH] PD: Fix crash in Loft::getSectionShape

The passed DocumentObject pointer can be null which is nowhere checked.
This fixes issue 19545

Fixes: 256ad7a01aa2 ("PartDesign: Loft Intelligence - Select the whole sketch if the selected shape is ...")
---
 src/Mod/PartDesign/App/FeatureLoft.cpp | 67 +++++++++++++++++---------
 1 file changed, 45 insertions(+), 22 deletions(-)

diff --git a/src/Mod/PartDesign/App/FeatureLoft.cpp b/src/Mod/PartDesign/App/FeatureLoft.cpp
index becc62d406..25bd92c722 100644
--- a/src/Mod/PartDesign/App/FeatureLoft.cpp
+++ b/src/Mod/PartDesign/App/FeatureLoft.cpp
@@ -65,32 +65,55 @@ short Loft::mustExecute() const
     return ProfileBased::mustExecute();
 }
 
-std::vector<Part::TopoShape>
-Loft::getSectionShape(const char *name,
-                      App::DocumentObject *obj,
-                      const std::vector<std::string> &subs,
-                      size_t expected_size)
+std::vector<Part::TopoShape> Loft::getSectionShape(const char* name,
+                                                   App::DocumentObject* obj,
+                                                   const std::vector<std::string>& subs,
+                                                   size_t expected_size)
 {
+    auto useSketch = [](App::DocumentObject* obj, const std::vector<std::string>& subs) {
+        // Be smart. If part of a sketch is selected, use the entire sketch unless it is a single
+        // vertex - backward compatibility (#16630)
+        if (!obj) {
+            return false;
+        }
+
+        auto subName = subs.empty() ? "" : subs.front();
+        return obj->isDerivedFrom<Part::Part2DObject>() && subName.find("Vertex") != 0;
+    };
+
     std::vector<TopoShape> shapes;
-    // Be smart. If part of a sketch is selected, use the entire sketch unless it is a single vertex -
-    // backward compatibility (#16630)
-    auto subName = subs.empty() ? "" : subs.front();
-    auto useEntireSketch = obj->isDerivedFrom<Part::Part2DObject>() &&  subName.find("Vertex") != 0;
-    if (subs.empty() || std::ranges::find(subs, std::string()) != subs.end() || useEntireSketch ) {
-        shapes.push_back(Part::Feature::getTopoShape(obj, Part::ShapeOption::ResolveLink | Part::ShapeOption::Transform));
-        if (shapes.back().isNull())
-            FC_THROWM(Part::NullShapeException, "Failed to get shape of "
-                          << name << " " << App::SubObjectT(obj, "").getSubObjectFullName(obj->getDocument()->getName()));
-    } else {
-        for (const auto &sub : subs) {
+    auto useEntireSketch = useSketch(obj, subs);
+    if (subs.empty() || std::ranges::find(subs, std::string()) != subs.end() || useEntireSketch) {
+        shapes.push_back(Part::Feature::getTopoShape(obj,
+                                                     Part::ShapeOption::ResolveLink
+                                                         | Part::ShapeOption::Transform));
+        if (shapes.back().isNull()) {
+            std::stringstream str;
+            str << "Failed to get shape of " << name;
+            if (obj) {
+                auto doc = obj->getDocument();
+                str << " " << App::SubObjectT(obj, "").getSubObjectFullName(doc->getName());
+            }
+            THROWM(Part::NullShapeException, str.str());
+        }
+    }
+    else {
+        for (const auto& sub : subs) {
             shapes.push_back(Part::Feature::getTopoShape(obj,
-                                                            Part::ShapeOption::NeedSubElement
-                                                          | Part::ShapeOption::ResolveLink
-                                                          | Part::ShapeOption::Transform,
+                                                         Part::ShapeOption::NeedSubElement
+                                                             | Part::ShapeOption::ResolveLink
+                                                             | Part::ShapeOption::Transform,
                                                          sub.c_str()));
-            if (shapes.back().isNull())
-                FC_THROWM(Part::NullShapeException, "Failed to get shape of " << name << " "
-                                                                              << App::SubObjectT(obj, sub.c_str()).getSubObjectFullName(obj->getDocument()->getName()));
+            if (shapes.back().isNull()) {
+                std::stringstream str;
+                str << "Failed to get shape of " << name;
+                if (obj) {
+                    auto doc = obj->getDocument();
+                    App::SubObjectT subObj(obj, sub.c_str());
+                    str << " " << subObj.getSubObjectFullName(doc->getName());
+                }
+                THROWM(Part::NullShapeException, str.str());
+            }
         }
     }
     auto compound = TopoShape(0).makeElementCompound(shapes, "", TopoShape::SingleShapeCompoundCreationPolicy::returnShape);