Version:           1.0.1+ #3214 (using KDE KDE 3.5.8)
Installed from:    SuSE RPMs
OS:                Linux

In http://websvn.kde.org/branches/extragear/kde3/network/konversation/src/server.cpp?annotate=736100#l2621, we have these lines:

                channel->remove(member);
                // If the nick is no longer listed in any channels or query list, delete it altogether.
                deleteNickIfUnlisted(member.data()->getNickInfo()->getNickname());


In line 2621, the iterator "member" is dereferenced and its content is removed from channel. Thus, a subsequent access of member.data() is invalid. However, in line 2623, member.data() is accessed and dereferenced, which should not happen.

In my case, it does not crash, but it could crash, because deallocated memory is accessed and used.

See this for further detail (note that in this case, line 2622 is where "channel->remove(member);" happens):

==13110==
==13110== Invalid read of size 4
==13110==    at 0x80AA3DC: KSharedPtr<ChannelNick>::operator->() (ksharedptr.h:164)
==13110==    by 0x8114ED3: Server::removeJoinedChannel(QString const&) (server.cpp:2624)
==13110==    by 0x8116EF2: Server::removeChannel(Channel*) (server.cpp:2151)
==13110==    by 0x80FD7AC: Channel::~Channel() (channel.cpp:323)
==13110==    by 0x4D62E6A: QWidget::~QWidget() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4E67395: QWidgetStack::~QWidgetStack() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4D62E6A: QWidget::~QWidget() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4E51843: QTabWidget::~QTabWidget() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x45FAC87: KTabWidget::~KTabWidget() (ktabwidget.cpp:75)
==13110==    by 0x4D62E6A: QWidget::~QWidget() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4E4AAF7: QSplitter::~QSplitter() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4D62E6A: QWidget::~QWidget() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4E20D42: QMainWindow::~QMainWindow() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x465875D: KMainWindow::~KMainWindow() (kmainwindow.cpp:322)
==13110==    by 0x808D462: KonversationMainWindow::~KonversationMainWindow() (konversationmainwindow.cpp:325)
==13110==    by 0x4D2A1BA: QObject::event(QEvent*) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4D635CB: QWidget::event(QEvent*) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4E1C101: QMainWindow::event(QEvent*) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x808CCEA: KonversationMainWindow::event(QEvent*) (konversationmainwindow.cpp:433)
==13110==    by 0x4CCC0AB: QApplication::internalNotify(QObject*, QEvent*) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4CCCE62: QApplication::notify(QObject*, QEvent*) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4918A61: KApplication::notify(QObject*, QEvent*) (kapplication.cpp:552)
==13110==    by 0x4CCD970: QApplication::sendPostedEvents(QObject*, int) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4CE2CBE: QEventLoop::enterLoop() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4CE2AC5: QEventLoop::exec() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4CCBC1E: QApplication::exec() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x8126EEF: main (main.cpp:112)
==13110==  Address 0x6406458 is 16 bytes inside a block of size 24 free'd
==13110==    at 0x4022156: operator delete(void*) (in /usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==13110==    by 0x8124812: QMapPrivate<QString, KSharedPtr<ChannelNick> >::remove(QMapIterator<QString, KSharedPtr<ChannelNick> >) (qmap.h:386)
==13110==    by 0x81248F4: QMap<QString, KSharedPtr<ChannelNick> >::remove(QMapIterator<QString, KSharedPtr<ChannelNick> >) (qmap.h:725)
==13110==    by 0x8114EC0: Server::removeJoinedChannel(QString const&) (server.cpp:2622)
==13110==    by 0x8116EF2: Server::removeChannel(Channel*) (server.cpp:2151)
==13110==    by 0x80FD7AC: Channel::~Channel() (channel.cpp:323)
==13110==    by 0x4D62E6A: QWidget::~QWidget() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4E67395: QWidgetStack::~QWidgetStack() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4D62E6A: QWidget::~QWidget() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4E51843: QTabWidget::~QTabWidget() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x45FAC87: KTabWidget::~KTabWidget() (ktabwidget.cpp:75)
==13110==    by 0x4D62E6A: QWidget::~QWidget() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4E4AAF7: QSplitter::~QSplitter() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4D62E6A: QWidget::~QWidget() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4E20D42: QMainWindow::~QMainWindow() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x465875D: KMainWindow::~KMainWindow() (kmainwindow.cpp:322)
==13110==    by 0x808D462: KonversationMainWindow::~KonversationMainWindow() (konversationmainwindow.cpp:325)
==13110==    by 0x4D2A1BA: QObject::event(QEvent*) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4D635CB: QWidget::event(QEvent*) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4E1C101: QMainWindow::event(QEvent*) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x808CCEA: KonversationMainWindow::event(QEvent*) (konversationmainwindow.cpp:433)
==13110==    by 0x4CCC0AB: QApplication::internalNotify(QObject*, QEvent*) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4CCCE62: QApplication::notify(QObject*, QEvent*) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4918A61: KApplication::notify(QObject*, QEvent*) (kapplication.cpp:552)
==13110==    by 0x4CCD970: QApplication::sendPostedEvents(QObject*, int) (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4CE2CBE: QEventLoop::enterLoop() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4CE2AC5: QEventLoop::exec() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x4CCBC1E: QApplication::exec() (in /usr/lib/qt3/lib/libqt-mt.so.3.3.8)
==13110==    by 0x8126EEF: main (main.cpp:112)