From 3b1c433daaf99193087c3999761fcb620f4e7340 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Fri, 29 Sep 2017 21:22:48 +0200
Subject: [PATCH] fix crashes when aborting linear pattern panel due access of
 null pointers

---
 src/Mod/PartDesign/Gui/ReferenceSelection.cpp  |  3 +++
 .../Gui/TaskLinearPatternParameters.cpp        | 18 +++++++++++-------
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/src/Mod/PartDesign/Gui/ReferenceSelection.cpp b/src/Mod/PartDesign/Gui/ReferenceSelection.cpp
index 18f469346a..1ec8d1431e 100644
--- a/src/Mod/PartDesign/Gui/ReferenceSelection.cpp
+++ b/src/Mod/PartDesign/Gui/ReferenceSelection.cpp
@@ -196,6 +196,9 @@ namespace PartDesignGui
 void getReferencedSelection(const App::DocumentObject* thisObj, const Gui::SelectionChanges& msg,
                             App::DocumentObject*& selObj, std::vector<std::string>& selSub)
 {
+    if (!thisObj)
+        return;
+
     if (strcmp(thisObj->getDocument()->getName(), msg.pDocName) != 0)
         return;
     
diff --git a/src/Mod/PartDesign/Gui/TaskLinearPatternParameters.cpp b/src/Mod/PartDesign/Gui/TaskLinearPatternParameters.cpp
index 8d0f1ac49d..338b3ca3d7 100644
--- a/src/Mod/PartDesign/Gui/TaskLinearPatternParameters.cpp
+++ b/src/Mod/PartDesign/Gui/TaskLinearPatternParameters.cpp
@@ -248,15 +248,19 @@ void TaskLinearPatternParameters::onSelectionChanged(const Gui::SelectionChanges
             // TODO check if this works correctly (2015-09-01, Fat-Zer)
             exitSelectionMode();
             std::vector<std::string> directions;
-            App::DocumentObject* selObj;
+            App::DocumentObject* selObj = nullptr;
             PartDesign::LinearPattern* pcLinearPattern = static_cast<PartDesign::LinearPattern*>(getObject());
-            getReferencedSelection(pcLinearPattern, msg, selObj, directions);
-            // Note: ReferenceSelection has already checked the selection for validity
-            if ( selectionMode == reference || selObj->isDerivedFrom ( App::Line::getClassTypeId () ) ) {
-                pcLinearPattern->Direction.setValue(selObj, directions);
+            if (pcLinearPattern) {
+                getReferencedSelection(pcLinearPattern, msg, selObj, directions);
 
-                recomputeFeature();
-                updateUI();
+                // Note: ReferenceSelection has already checked the selection for validity
+                if (selObj && (selectionMode == reference ||
+                               selObj->isDerivedFrom(App::Line::getClassTypeId()))) {
+                    pcLinearPattern->Direction.setValue(selObj, directions);
+
+                    recomputeFeature();
+                    updateUI();
+                }
             }
         }
     }