From 111ee58c065602bfcde520b54f44809d854e73f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Morten=20Johan=20S=C3=B8rvig?=
 <morten.sorvig@theqtcompany.com>
Date: Tue, 18 Aug 2015 11:39:01 +0200
Subject: [PATCH] Prevent QGestureManager crash.

Use QPointer to prevent dereferencing stale pointers
stored in m_gestureTargets.

Add null pointer tests in addition to the Q_ASSERTs
on the pointers returned by m_gestureTargets.value().
The intention is to assert in debug mode but keep
going in release mode.

Change-Id: Icdef8cc02040bddc88f4bcb268e9ca0ac252557d
Task-number: QTBUG-46264
Reviewed-by: Pawel Kurdybacha <pawel.kurdybacha@gmail.com>
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@theqtcompany.com>
---
 src/widgets/kernel/qgesturemanager.cpp | 5 ++++-
 src/widgets/kernel/qgesturemanager_p.h | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/widgets/kernel/qgesturemanager.cpp b/src/widgets/kernel/qgesturemanager.cpp
index b5d3a56d3f..8b918a72a2 100644
--- a/src/widgets/kernel/qgesturemanager.cpp
+++ b/src/widgets/kernel/qgesturemanager.cpp
@@ -405,6 +405,8 @@ void QGestureManager::cancelGesturesForChildren(QGesture *original)
     Q_ASSERT(original);
     QWidget *originatingWidget = m_gestureTargets.value(original);
     Q_ASSERT(originatingWidget);
+    if (!originatingWidget)
+        return;
 
     // iterate over all active gestures and all maybe gestures
     // for each find the owner
@@ -565,7 +567,8 @@ void QGestureManager::getGestureTargets(const QSet<QGesture*> &gestures,
     foreach (QGesture *gesture, gestures) {
         QWidget *receiver = m_gestureTargets.value(gesture, 0);
         Q_ASSERT(receiver);
-        gestureByTypes[gesture->gestureType()].insert(receiver, gesture);
+        if (receiver)
+            gestureByTypes[gesture->gestureType()].insert(receiver, gesture);
     }
 
     // for each gesture type
diff --git a/src/widgets/kernel/qgesturemanager_p.h b/src/widgets/kernel/qgesturemanager_p.h
index 8ba253d17e..4e349ac731 100644
--- a/src/widgets/kernel/qgesturemanager_p.h
+++ b/src/widgets/kernel/qgesturemanager_p.h
@@ -117,7 +117,7 @@ private:
     QHash<QGesture *, QGestureRecognizer *> m_gestureToRecognizer;
     QHash<QGesture *, QObject *> m_gestureOwners;
 
-    QHash<QGesture *, QWidget *> m_gestureTargets;
+    QHash<QGesture *, QPointer<QWidget> > m_gestureTargets;
 
     int m_lastCustomGestureId;