I have installed Qt 5.8.0 and a number of KF5 projects built as much as possible against the packages provided by/for an up-to-date Kubuntu 14.04LTS system. Just now I got a crash that reflects a bug either in DBus or in the memory allocation routines it uses. I wasn't interacting with the machine when the crash occurred so I can only provide the backtrace below.
Application: digiKam (digikam), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7ff88dbe1880 (LWP 28796))]
[Snipped irrelevant threads]
Thread 1 (Thread 0x7ff88dbe1880 (LWP 28796)):
[KCrash Handler]
#6 0x00007ff888f85809 in malloc_consolidate (av=av@entry=0x7ff858000020) at malloc.c:4159
#7 0x00007ff888f878b8 in _int_malloc (av=av@entry=0x7ff858000020, bytes=bytes@entry=9425) at malloc.c:3425
#8 0x00007ff888f89311 in _int_realloc (av=0x7ff858000020, oldp=0x7ff858063130, oldsize=288, nb=9440) at malloc.c:4288
#9 0x00007ff888f8a2f9 in __GI___libc_realloc (oldmem=0x7ff858063140, bytes=9420) at malloc.c:3031
#10 0x00007ff87aa56f9a in dbus_realloc (memory=<optimized out>, bytes=<optimized out>) at ../../dbus/dbus-memory.c:677
#11 0x00007ff87aa5737f in reallocate_for_length (new_length=9412, real=0x7ff8580fda30) at ../../dbus/dbus-string.c:352
#12 set_length (real=real@entry=0x7ff8580fda30, new_length=9412) at ../../dbus/dbus-string.c:393
#13 0x00007ff87aa57466 in open_gap (len=9216, dest=0x7ff8580fda30, insert_at=196) at ../../dbus/dbus-string.c:414
#14 0x00007ff87aa575ab in copy (start=start@entry=0, len=len@entry=9216, dest=dest@entry=0x7ff8580fda30, insert_at=insert_at@entry=196, source=0x7ffe958253b0) at ../../dbus/dbus-string.c:1221
#15 0x00007ff87aa57dd5 in _dbus_string_copy_len (source=source@entry=0x7ffe958253b0, start=start@entry=0, len=len@entry=9216, dest=dest@entry=0x7ff8580fda30, insert_at=insert_at@entry=196) at ../../dbus/dbus-string.c:1391
#16 0x00007ff87aa56969 in marshal_1_octets_array (byte_order=<optimized out>, pos_after=0x7ffe95825480, n_elements=9216, value=<optimized out>, insert_at=196, str=0x7ff8580fda30) at ../../dbus/dbus-marshal-basic.c:929
#17 _dbus_marshal_write_fixed_multi (str=0x7ff8580fda30, insert_at=196, element_type=element_type@entry=121, value=value@entry=0x7ffe95825448, n_elements=n_elements@entry=9216, byte_order=<optimized out>, pos_after=pos_after@entry=0x7ffe95825480) at ../../dbus/dbus-marshal-basic.c:1106
#18 0x00007ff87aa44ce5 in _dbus_type_writer_write_fixed_multi (writer=writer@entry=0x7ffe95825460, element_type=element_type@entry=121, value=value@entry=0x7ffe95825448, n_elements=9216) at ../../dbus/dbus-marshal-recursive.c:2376
#19 0x00007ff87aa48466 in dbus_message_iter_append_fixed_array (iter=iter@entry=0x7ffe95825450, element_type=element_type@entry=121, value=value@entry=0x7ffe95825448, n_elements=<optimized out>) at ../../dbus/dbus-message.c:2745
#20 0x00007ff8860068e6 in q_dbus_message_iter_append_fixed_array (n_elements=<optimized out>, value=0x7ffe95825448, element_type=121, iter=0x7ffe95825450) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbus_symbols_p.h:303
#21 append (arg=..., this=0x458cd70) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusmarshaller.cpp:179
#22 QDBusArgument::operator<< (this=0x7ffe95825530, arg=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusargument.cpp:547
#23 0x00007ff88234be6f in operator<< (image=..., argument=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_kf5_KF5-Frameworks/kf5-knotifications/work/knotifications-5.35.0/src/imageconverter.cpp:42
#24 qDBusMarshallHelper<ImageConverter::SpecImage> (arg=..., t=0x1b300a0) at /opt/local/include/qt5/QtDBus/qdbusmetatype.h:68
#25 0x00007ff88600cb28 in QDBusMetaType::marshall (arg=..., id=<optimized out>, data=data@entry=0x1b300a0) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusmetatype.cpp:256
#26 0x00007ff886007abb in QDBusMarshaller::appendRegisteredType (this=this@entry=0x7ffe958256c0, arg=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusmarshaller.cpp:531
#27 0x00007ff8860092c6 in QDBusMarshaller::appendVariantInternal (this=this@entry=0x7ffe958256c0, arg=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusmarshaller.cpp:504
#28 0x00007ff88600b724 in QDBusMarshaller::append (this=0x5625b40, arg=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusmarshaller.cpp:221
#29 0x00007ff88600a670 in QDBusArgument::operator<< (this=this@entry=0x7ffe95825830, arg=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusargument.cpp:511
#30 0x00007ff8875b3c3e in operator<< (map=..., arg=...) at /opt/local/include/qt5/QtDBus/qdbusargument.h:347
#31 qDBusMarshallHelper<QMap<QString, QVariant> > (arg=..., t=<optimized out>) at /opt/local/include/qt5/QtDBus/qdbusmetatype.h:68
#32 0x00007ff88600cb28 in QDBusMetaType::marshall (arg=..., id=<optimized out>, data=data@entry=0x6522ce0) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusmetatype.cpp:256
#33 0x00007ff886007abb in QDBusMarshaller::appendRegisteredType (this=this@entry=0x7ffe958259e0, arg=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusmarshaller.cpp:531
#34 0x00007ff8860092c6 in QDBusMarshaller::appendVariantInternal (this=this@entry=0x7ffe958259e0, arg=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusmarshaller.cpp:504
#35 0x00007ff885fd95d0 in QDBusMessagePrivate::toDBusMessage (message=..., capabilities=..., error=error@entry=0x7ffe95825bb0) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusmessage.cpp:194
#36 0x00007ff885fd3fa0 in QDBusConnectionPrivate::sendWithReplyAsync (this=0x7ff8580030f0, message=..., receiver=receiver@entry=0x0, returnMethod=returnMethod@entry=0x0, errorMethod=errorMethod@entry=0x0, timeout=timeout@entry=-1) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusintegrator.cpp:2141
#37 0x00007ff885fc2688 in QDBusConnection::asyncCall (this=this@entry=0x7ffe95825d10, message=..., timeout=timeout@entry=-1) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/dbus/qdbusconnection.cpp:703
#38 0x00007ff8823465f0 in NotifyByPopupPrivate::sendNotificationToGalagoServer (this=0x63e4860, notification=<optimized out>, notification@entry=0x57e74b0, notifyConfig_nocheck=..., update=update@entry=false) at /opt/local/var/lnxports/build/_opt_local_site-ports_kf5_KF5-Frameworks/kf5-knotifications/work/knotifications-5.35.0/src/notifybypopup.cpp:738
#39 0x00007ff882349135 in NotifyByPopup::notify (this=0x64db280, notification=0x57e74b0, notifyConfig=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_kf5_KF5-Frameworks/kf5-knotifications/work/knotifications-5.35.0/src/notifybypopup.cpp:243
#40 0x00007ff88232ac4b in KNotificationManager::notify (this=0x7ff882577300 <(anonymous namespace)::Q_QGS_s_self::innerFunction()::holder>, n=0x57e74b0) at /opt/local/var/lnxports/build/_opt_local_site-ports_kf5_KF5-Frameworks/kf5-knotifications/work/knotifications-5.35.0/src/knotificationmanager.cpp:242
#41 0x00007ff8823278a4 in KNotification::sendEvent (this=0x57e74b0) at /opt/local/var/lnxports/build/_opt_local_site-ports_kf5_KF5-Frameworks/kf5-knotifications/work/knotifications-5.35.0/src/knotification.cpp:425
#42 0x00007ff889ab8121 in QObject::event (this=0x57e74b0, e=<optimized out>) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/corelib/kernel/qobject.cpp:1263
#43 0x00007ff88a8008ac in QApplicationPrivate::notify_helper (this=<optimized out>, receiver=0x57e74b0, e=0x3c6a500) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/widgets/kernel/qapplication.cpp:3745
#44 0x00007ff88a807b21 in QApplication::notify (this=0x7ffe95826900, receiver=0x57e74b0, e=0x3c6a500) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/widgets/kernel/qapplication.cpp:3502
#45 0x00007ff889a8c018 in QCoreApplication::notifyInternal2 (receiver=0x57e74b0, event=event@entry=0x3c6a500) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/corelib/kernel/qcoreapplication.cpp:995
#46 0x00007ff889a8e67d in sendEvent (event=0x3c6a500, receiver=<optimized out>) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/corelib/kernel/qcoreapplication.h:231
#47 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0x76f170) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/corelib/kernel/qcoreapplication.cpp:1655
#48 0x00007ff889a8eae8 in QCoreApplication::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/corelib/kernel/qcoreapplication.cpp:1509
#49 0x00007ff889ade173 in postEventSourceDispatch (s=0x878770) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/corelib/kernel/qeventdispatcher_glib.cpp:276
#50 0x00007ff87fd300f7 in g_main_dispatch (context=0x7ff8640016f0) at gmain.c:3191
#51 g_main_context_dispatch (context=context@entry=0x7ff8640016f0) at gmain.c:3844
#52 0x00007ff87fd30348 in g_main_context_iterate (context=context@entry=0x7ff8640016f0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at gmain.c:3917
#53 0x00007ff87fd303ec in g_main_context_iteration (context=0x7ff8640016f0, may_block=may_block@entry=1) at gmain.c:3978
#54 0x00007ff889ade57f in QEventDispatcherGlib::processEvents (this=0x87c770, flags=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/corelib/kernel/qeventdispatcher_glib.cpp:423
#55 0x00007ff889a8a17a in QEventLoop::exec (this=this@entry=0x7ffe95826490, flags=..., flags@entry=...) at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/corelib/kernel/qeventloop.cpp:212
#56 0x00007ff889a92524 in QCoreApplication::exec () at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/corelib/kernel/qcoreapplication.cpp:1268
#57 0x00007ff889ff6b8c in QGuiApplication::exec () at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/gui/kernel/qguiapplication.cpp:1661
#58 0x00007ff88a800805 in QApplication::exec () at /opt/local/var/lnxports/build/_opt_local_site-ports_aqua_qt5-kde-devel/qt5-kde-devel/work/qt-everywhere-opensource-src-5.8.0/qtbase/src/widgets/kernel/qapplication.cpp:2921
#59 0x0000000000405fd1 in main (argc=<optimized out>, argv=<optimized out>) at /opt/local/var/lnxports/build/_opt_local_site-ports_kf5_kf5-digikam/kf5-digikam/work/digikam-5.5.0/core/app/main/main.cpp:240
