Fix out of bounds reads in Array.concat

In some cases, when our simple array data had an offset and
data would wrap around, ArrayData::append would write out
of bounds data into the new array, leading to crashes.

Task-number: QTBUG-51581
Change-Id: I55172542ef0b94d263cfc9a17d7ca49ec6c3a565
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 14 insertions, 0 deletions

diff --git a/tests/auto/qml/qjsengine/tst_qjsengine.cpp b/tests/auto/qml/qjsengine/tst_qjsengine.cpp
index 8ffaa96569..8a017fd573 100644
--- a/tests/auto/qml/qjsengine/tst_qjsengine.cpp
+++ b/tests/auto/qml/qjsengine/tst_qjsengine.cpp
@@ -128,6 +128,7 @@ private slots:
     void JSONparse();
     void arraySort();
     void lookupOnDisappearingProperty();
+    void arrayConcat();
 
     void qRegExpInport_data();
     void qRegExpInport();
@@ -3009,6 +3010,19 @@ void tst_QJSEngine::lookupOnDisappearingProperty()
     QVERIFY(func.call(QJSValueList()<< o).isUndefined());
 }
 
+void tst_QJSEngine::arrayConcat()
+{
+    QJSEngine eng;
+    QJSValue v = eng.evaluate("var x = [1, 2, 3, 4, 5, 6];"
+                              "var y = [];"
+                              "for (var i = 0; i < 5; ++i)"
+                              "    x.shift();"
+                              "for (var i = 10; i < 13; ++i)"
+                              "   x.push(i);"
+                              "x.toString();");
+    QCOMPARE(v.toString(), QString::fromLatin1("6,10,11,12"));
+}
+
 static QRegExp minimal(QRegExp r) { r.setMinimal(true); return r; }
 
 void tst_QJSEngine::qRegExpInport_data()