/usr/lib/arm-linux-gnueabihf/qt5/bin/qmlscene:11:QCoreApplication::notifyInternal:MInputContext::updatePreeditInternally:MInputContext::updatePreedit:MInputContext::qt_static_metacall:QMetaObject::activate

[errors.ubuntu.com bug bridge]

The Ubuntu Error Tracker has been receiving reports about a problem regarding qtdeclarative-opensource-src. This problem was most recently seen with version 5.3.0-3ubuntu8, the problem page at https://errors.ubuntu.com/problem/50ffdb4caf743ab085b5cdaa290c32dad7c24c7e contains more details.

[Timo Jyrinki (timo-jyrinki)]

Based on the stacktrace qtbase is a more likely place for the problem, since QDBus is shown.

A reproducable test case would be useful, and with that it would be great if Qt 5.3.1 could be tested as instructed at https://wiki.ubuntu.com/Touch/QtTesting. That would tell if there is a fix available upstream to cherry-pick.

[Chris Gagnon (chris.gagnon)]

Unfortunately there are no steps to reproduce, a test that randomly clicks and swipes on the screen found this crash. I've seen issues in the systems-settings app not responding to dbus issues after flight mode is used, I'll try to reproduce this crash manually.

[Chris Gagnon (chris.gagnon)]

https://errors.ubuntu.com/oops/9a0c99f8-1e6d-11e4-b766-fa163e75317b looks like the same issue, but we didn't get a good stack trace.

[Chris Gagnon (chris.gagnon)]

I have another crash here that looks like the same issue .
https://errors.ubuntu.com/bucket/?id=/usr/bin/dialer-app%3A11%3AQCoreApplication%3A%3AnotifyInternal%3AMInputContext%3A%3AupdatePreeditInternally%3AMInputContext%3A%3AupdatePreedit%3AMInputContext%3A%3Aqt_static_metacall%3AQMetaObject%3A%3Aactivate

[Chris Gagnon (chris.gagnon)]

https://errors.ubuntu.com/bucket/?id=/usr/bin/address-book-app%3A11%3AQCoreApplication%3A%3AnotifyInternal%3AMInputContext%3A%3AupdatePreeditInternally%3AMInputContext%3A%3AupdatePreedit%3AMInputContext%3A%3Aqt_static_metacall%3AQMetaObject%3A%3Aactivate also looks like the same issue

[Timo Jyrinki (timo-jyrinki)]

I searched for qplatforminputcontext and dbus related commits in 5.3.x, but none seemed to touch the places in code where the trace points to. But in doing that, I figured out that while QDBus is in qtbase, "MInputContext" is not in platforminputcontext (in qtbase) where I thought it'd be, but instead it's in maliit-framework.

Michael, could you take a look at this crasher in MInputContext::updatePreedit?

[Michael Sheldon (michael-sheldon)]

I think this is being caused by the unchecked use of qGuiApp->focusObject() in minputcontext.cpp:488, it looks like its possible to cause a crash by typing whilst changing focus, resulting in maliit attempting to send the event somewhere invalid. There seems to be a fair amount of unchecked uses of qGuiApp->focusObject() in minputcontext.cpp, however it looks like this was actually addressed upstream nearly a year ago: https://github.com/maliit/framework/commit/17fdf8699c53ddfb2c15df8e11d46804e782fec5

I'll see if we can get our maliit-framework package updated and hopefully that should resolve this.