Zeal::ListModel::removeDocset didn't check NULL leads crash

[comicfans]

git version 58e2080

docset downloaded complete trigger this problem.

listmodel.cpp:198

DocsetItem *docsetItem = m_docsetItems.take(name); --->docsetItem = 0x0
qDeleteAll(docsetItem->groups);  --->crash

backtrace shows as

#0  0x000000000041d850 in QListData::end (this=0x10) at /usr/include/qt/QtCore/qlist.h:109
#1  0x0000000000440a04 in QList<Zeal::ListModel::GroupItem*>::end (this=0x10) at /usr/include/qt/QtCore/qlist.h:304
#2  0x000000000043ffca in qDeleteAll<QList<Zeal::ListModel::GroupItem*> > (c=...) at /usr/include/qt/QtCore/qalgorithms.h:325
#3  0x000000000043f8d2 in Zeal::ListModel::removeDocset (this=0x75fad0, name=...) at registry/listmodel.cpp:199   
#4  0x00000000004416ce in QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<QString const&>, void, void (Zeal::ListModel::*)(QString const&)>::call (f=
    (void (Zeal::ListModel::*)(Zeal::ListModel * const, const QString &)) 0x43f836 <Zeal::ListModel::removeDocset(QString const&)>, o=0x75fad0, arg=0x7fffffffc830) at /usr/include/qt/QtCore/qobjectdefs_impl.h:501
#5  0x0000000000441533 in QtPrivate::FunctionPointer<void (Zeal::ListModel::*)(QString const&)>::call<QtPrivate::List<QString const&>, void> (f=
    (void (Zeal::ListModel::*)(Zeal::ListModel * const, const QString &)) 0x43f836 <Zeal::ListModel::removeDocset(QString const&)>, o=0x75fad0, arg=0x7fffffffc830) at /usr/include/qt/QtCore/qobjectdefs_impl.h:520
#6  0x00000000004411c5 in QtPrivate::QSlotObject<void (Zeal::ListModel::*)(QString const&), QtPrivate::List<QString const&>, void>::impl (which=1, this_=0x75ffb0, r=0x75fad0, a=0x7fffffffc830, ret=0x0)
    at /usr/include/qt/QtCore/qobject_impl.h:143
#7  0x00007ffff2f08fb7 in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQt5Core.so.5
#8  0x0000000000474cf3 in Zeal::DocsetRegistry::docsetAboutToBeRemoved (this=0x73d410, _t1=...) at ../.moc/moc_docsetregistry.cpp:183
#9  0x0000000000439f21 in Zeal::DocsetRegistry::remove (this=0x73d410, name=...) at registry/docsetregistry.cpp:77
#10 0x000000000045a85b in Zeal::SettingsDialog::downloadCompleted (this=0x760050) at ui/settingsdialog.cpp:334

Havn't trace whole controlflow, not sure if removeDocset should check NULL here.

[trollixx]

Hi,

Thank you for taking time and debugging the crash. Your assumption is correct, ListModel::removeDocset should never be called with non-existent docset.

I wonder what docset were you downloading or updating?

[comicfans]

sorry for my late reply...

1. first start, when docset UI appears , it seems display duplicate docsets. (same list repeast twice).
2. then I choose Qt4 Qt5 android docset and begin downloading. not sure which docset triggered bug.
3. maybe my internet connection lost , or DNS didn't reply quickly enough, one docset failed to download completely.
4. this bug fired

hopeful this can help.

[lock]

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