Bug 31058 – [Qt] QWebSettings using unitialized values

• Status: RESOLVED
• Resolution: INVALID
• Component: WebKit Qt

The QWebSettings(WebCore::Settings* settings) ctor does access unitialized values. The current code:

QWebSettings::QWebSettings(WebCore::Settings* settings)
    : d(new QWebSettingsPrivate(settings))
{
    d->settings = settings;
    d->apply();
    allSettings()->append(d);
}


does not correctly initialize d->printingMinimumShrinkFactor  d->printingMaximumShrinkFactor and d->offlineStorageDefaultQuota, since the QWebSettingsPrivate ctor also does not set those values.

But the inside QWebSettignsPrivate::apply() d->printingMinimumShrinkFactor and d->printingMaximumShrinkFactor are accessed. This generates the following valgrind warnings:


  40: ==10098== Conditional jump or move depends on uninitialised value(s) 
   41: ==10098==    at 0x9D04BB9: QWebSettingsPrivate::apply() (in /home/apoenitz/dev/qt-4.6/lib/libQtWebKitMyns.so.4.6.0) 
   42: ==10098==    by 0x9D0591A: QWebSettings::QWebSettings(WebCore::Settings*) (in /home/apoenitz/dev/qt-4.6/lib/libQtWebKitMyns.so.4.6.0) 
   43: ==10098==    by 0x9CF16AF: QWebPagePrivate::QWebPagePrivate(QWebPage*) (in /home/apoenitz/dev/qt-4.6/lib/libQtWebKitMyns.so.4.6.0) 
   44: ==10098==    by 0x9CF19FE: QWebPage::QWebPage(myns::QObject*) (in /home/apoenitz/dev/qt-4.6/lib/libQtWebKitMyns.so.4.6.0) 
   45: ==10098==    by 0x93E6B65: HelpPage::HelpPage(Help::Internal::CentralWidget*, myns::QHelpEngine*, myns::QObject*) (helpviewer.cpp:171) 
   46: ==10098==    by 0x93E6D0D: HelpViewer::HelpViewer(myns::QHelpEngine*, Help::Internal::CentralWidget*) (helpviewer.cpp:240) 
   47: ==10098==    by 0x93C03E4: Help::Internal::HelpPlugin::createRightPaneSideBar() (helpplugin.cpp:494) 
   48: ==10098==    by 0x93C60E1: Help::Internal::HelpPlugin::initialize(myns::QStringList const&, myns::QString*) (helpplugin.cpp:408) 
   49: ==10098==    by 0x40469F6: ExtensionSystem::Internal::PluginSpecPrivate::initializePlugin() (pluginspec.cpp:827) 
   50: ==10098==    by 0x403EF99: ExtensionSystem::Internal::PluginManagerPrivate::loadPlugin(ExtensionSystem::PluginSpec*, ExtensionSystem::PluginSpec::State) (pluginmanager.cpp:677) 
   51: ==10098==    by 0x403FE8E: ExtensionSystem::Internal::PluginManagerPrivate::loadPlugins() (pluginmanager.cpp:582) 
   52: ==10098==    by 0x404000F: ExtensionSystem::PluginManager::loadPlugins() (pluginmanager.cpp:246) 
   53: ==10098==  Uninitialised value was created by a heap allocation 
   54: ==10098==    at 0x40269EE: operator new(unsigned int) (vg_replace_malloc.c:224) 
   55: ==10098==    by 0x9D058E5: QWebSettings::QWebSettings(WebCore::Settings*) (in /home/apoenitz/dev/qt-4.6/lib/libQtWebKitMyns.so.4.6.0) 
   56: ==10098==    by 0x9CF16AF: QWebPagePrivate::QWebPagePrivate(QWebPage*) (in /home/apoenitz/dev/qt-4.6/lib/libQtWebKitMyns.so.4.6.0) 
   57: ==10098==    by 0x9CF19FE: QWebPage::QWebPage(myns::QObject*) (in /home/apoenitz/dev/qt-4.6/lib/libQtWebKitMyns.so.4.6.0) 
   58: ==10098==    by 0x93E6B65: HelpPage::HelpPage(Help::Internal::CentralWidget*, myns::QHelpEngine*, myns::QObject*) (helpviewer.cpp:171) 
   59: ==10098==    by 0x93E6D0D: HelpViewer::HelpViewer(myns::QHelpEngine*, Help::Internal::CentralWidget*) (helpviewer.cpp:240) 
   60: ==10098==    by 0x93C03E4: Help::Internal::HelpPlugin::createRightPaneSideBar() (helpplugin.cpp:494) 
   61: ==10098==    by 0x93C60E1: Help::Internal::HelpPlugin::initialize(myns::QStringList const&, myns::QString*) (helpplugin.cpp:408) 
   62: ==10098==    by 0x40469F6: ExtensionSystem::Internal::PluginSpecPrivate::initializePlugin() (pluginspec.cpp:827) 
   63: ==10098==    by 0x403EF99: ExtensionSystem::Internal::PluginManagerPrivate::loadPlugin(ExtensionSystem::PluginSpec*, ExtensionSystem::PluginSpec::State) (pluginmanager.cpp:677) 
   64: ==10098==    by 0x403FE8E: ExtensionSystem::Internal::PluginManagerPrivate::loadPlugins() (pluginmanager.cpp:582) 
   65: ==10098==    by 0x404000F: ExtensionSystem::PluginManager::loadPlugins() (pluginmanager.cpp:246)

[Manish Gupta]

Created attachment 42763 [details]
Providing Initialization of variables in constructor

[Eric Seidel (no email)]

Comment on attachment 42763 [details]
Providing Initialization of variables in constructor

This does not comply with teh webkit style guide.  http://webkit.org/coding/coding-style.html

Please run check-webkit-style against the file or the patch.

[Manish Gupta]

Created attachment 42868 [details]
initialization of variables in constructor, webkit compliant code style

[Simon Hausmann]

Comment on attachment 42868 [details]
initialization of variables in constructor, webkit compliant code style

Good catch!

[Jocelyn Turcotte]

This is a duplicate of bug #30755.
Both bugs have proposed patches so I'm not in position of knowing which one should be closed as duplicate.

Also note that both submitted patches depends on changes of bug #29042 which have been reverted to be postponed to 4.7.

Please consider it before committing.

[Kenneth Rohde Christiansen]

Comment on attachment 42868 [details]
initialization of variables in constructor, webkit compliant code style

The code was been reverted, so marking r-.

I also noticed these issues yesterday due to crashes in the DRT, but didn't review this patch as Benjamin and me decided to revert the patch introducing the change instead,

[Simon Hausmann]

Closing this bug as rolling out the original patch also fixed this UMR.