From 17d231039b53c03e67d025f1f72bbd529e98fcbd Mon Sep 17 00:00:00 2001
From: Sergio Martins <sergio.martins@kdab.com>
Date: Wed, 13 Dec 2017 21:29:21 +0000
Subject: [PATCH] Don't crash with null receiver/context in new-style connects

old style connects have protection against null sender and null receiver,
but new style only had against null sender.

Change-Id: Ie555ac078412918e60c3b60830fe1f3abfb7f5af
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
---
 src/corelib/kernel/qobject.cpp                    |  2 +-
 tests/auto/corelib/kernel/qobject/tst_qobject.cpp | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index 3f50716cd73..086b8a51ba9 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -4796,7 +4796,7 @@ QMetaObject::Connection QObjectPrivate::connectImpl(const QObject *sender, int s
                                              QtPrivate::QSlotObjectBase *slotObj, Qt::ConnectionType type,
                                              const int *types, const QMetaObject *senderMetaObject)
 {
-    if (!sender || !slotObj || !senderMetaObject) {
+    if (!sender || !receiver || !slotObj || !senderMetaObject) {
         qWarning("QObject::connect: invalid null parameter");
         if (slotObj)
             slotObj->destroyIfLastRef();
diff --git a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
index 642d48d7216..f1e58921c0c 100644
--- a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
+++ b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
@@ -150,6 +150,7 @@ private slots:
     void deleteLaterInAboutToBlockHandler();
     void mutableFunctor();
     void checkArgumentsForNarrowing();
+    void nullReceiver();
 };
 
 struct QObjectCreatedOnShutdown
@@ -7380,6 +7381,16 @@ void tst_QObject::checkArgumentsForNarrowing()
 #undef FITS
 }
 
+void tst_QObject::nullReceiver()
+{
+    QObject o;
+    QObject *nullObj = nullptr; // Passing nullptr directly doesn't compile with gcc 4.8
+    QVERIFY(!connect(&o, &QObject::destroyed, nullObj, &QObject::deleteLater));
+    QVERIFY(!connect(&o, &QObject::destroyed, nullObj, [] {}));
+    QVERIFY(!connect(&o, &QObject::destroyed, nullObj, Functor_noexcept()));
+    QVERIFY(!connect(&o, SIGNAL(destroyed()), nullObj, SLOT(deleteLater())));
+}
+
 // Test for QtPrivate::HasQ_OBJECT_Macro
 Q_STATIC_ASSERT(QtPrivate::HasQ_OBJECT_Macro<tst_QObject>::Value);
 Q_STATIC_ASSERT(!QtPrivate::HasQ_OBJECT_Macro<SiblingDeleter>::Value);