From 5609f4a87971ccb9068799e1292fb73c058e8a6e Mon Sep 17 00:00:00 2001
From: Hugo Mercier <hugo.mercier@oslandia.com>
Date: Fri, 1 Feb 2019 14:20:30 +0100
Subject: [PATCH] Avoid undefined behaviour with signed integer overflow

---
 src/gui/editorwidgets/qgsrangewidgetwrapper.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp b/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp
index 9015d23c23f..15570a8bdb9 100644
--- a/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp
@@ -144,12 +144,12 @@ void QgsRangeWidgetWrapper::initWidget( QWidget *editor )
     int minval = min.toInt();
     if ( allowNull )
     {
-      int stepval = step.isValid() ? step.toInt() : 1;
-      int newMinval = minval - stepval;
+      uint stepval = step.isValid() ? step.toUInt() : 1;
       // make sure there is room for a new value (i.e. signed integer does not overflow)
-      if ( newMinval < minval )
+      int minvalOverflow = uint( minval ) - stepval;
+      if ( minvalOverflow < minval )
       {
-        minval = newMinval;
+        minval = minvalOverflow;
       }
       mIntSpinBox->setValue( minval );
       QgsSpinBox *intSpinBox( qobject_cast<QgsSpinBox *>( mIntSpinBox ) );