Fix data corruption when reading byte arrays from QSettings

On macOS, the code that read the plist is using
QByteArray::fromRawCFData. When we return the data directly
we need to detach the QByteArray so that it does not point
CFData's data that will get deallocated just after the call.

Task-number: QTBUG-58531
Change-Id: If829a304b986c99c8fc2aeeb992f2d539a4eef3a
Reviewed-by: Thiago Macieira <[email protected]>
Reviewed-by: Tor Arne Vestbø <[email protected]>

4 files changed, 25 insertions, 1 deletions

diff --git a/src/corelib/io/qsettings_mac.cpp b/src/corelib/io/qsettings_mac.cpp
index b79abfb8748..0e3520441e2 100644
--- a/src/corelib/io/qsettings_mac.cpp
+++ b/src/corelib/io/qsettings_mac.cpp
@@ -269,8 +269,10 @@ static QVariant qtValue(CFPropertyListRef cfvalue)
 
         // Fast-path for QByteArray, so that we don't have to go
         // though the expensive and lossy conversion via UTF-8.
-        if (!byteArray.startsWith('@'))
+        if (!byteArray.startsWith('@')) {
+            byteArray.detach();
             return byteArray;
+        }
 
         const QString str = QString::fromUtf8(byteArray.constData(), byteArray.size());
         return QSettingsPrivate::stringToVariant(str);
diff --git a/tests/auto/corelib/io/qsettings/qsettings.qrc b/tests/auto/corelib/io/qsettings/qsettings.qrc
index c0be7e013fa..c664a6f68cc 100644
--- a/tests/auto/corelib/io/qsettings/qsettings.qrc
+++ b/tests/auto/corelib/io/qsettings/qsettings.qrc
@@ -5,6 +5,7 @@
         <file>resourcefile3.ini</file>
         <file>resourcefile4.ini</file>
         <file>resourcefile5.ini</file>
+        <file>resourcefile6.plist</file>
         <file>bom.ini</file>
     </qresource>
 </RCC>
diff --git a/tests/auto/corelib/io/qsettings/resourcefile6.plist b/tests/auto/corelib/io/qsettings/resourcefile6.plist
new file mode 100644
index 00000000000..6f994accac6
--- /dev/null
+++ b/tests/auto/corelib/io/qsettings/resourcefile6.plist
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>passwordData</key>
+	<data>
+	RBxVAAsDVsO/
+	</data>
+</dict>
+</plist>
diff --git a/tests/auto/corelib/io/qsettings/tst_qsettings.cpp b/tests/auto/corelib/io/qsettings/tst_qsettings.cpp
index f94349fd025..199ab442c44 100644
--- a/tests/auto/corelib/io/qsettings/tst_qsettings.cpp
+++ b/tests/auto/corelib/io/qsettings/tst_qsettings.cpp
@@ -178,6 +178,7 @@ private slots:
 
     void testByteArray_data();
     void testByteArray();
+    void testByteArrayNativeFormat();
     void iniCodec();
     void bom();
     void embeddedZeroByte_data();
@@ -670,6 +671,16 @@ void tst_QSettings::testByteArray()
     }
 }
 
+void tst_QSettings::testByteArrayNativeFormat()
+{
+#ifndef Q_OS_MACOS
+    QSKIP("This test is specific to macOS plist reading.");
+#else
+    QSettings settings(":/resourcefile6.plist", QSettings::NativeFormat);
+    QCOMPARE(settings.value("passwordData"), QVariant(QByteArray::fromBase64("RBxVAAsDVsO/")));
+#endif
+}
+
 void tst_QSettings::iniCodec()
 {
     {