Qt: fix crash when closing RTP player while playing

For some time, the RTP Player has been crashing for me (Arch Linux, Qt
5.7.0) when the RTP Player is active (affects also Wireshark 2.0.5).

This call trace was observed:

    + RtpPlayerDialog::reject (closing dialog via Escape / Close button)
      + RtpAudioStream::stopPlaying
        + RtpAudioStream::outputStateChanged(QAudio::StoppedState)
          + QAudioOutput::deleteLater   // problematic!
      + RtpPlayerDialog::~RtpPlayerDialog
        + RtpAudioStream::~RtpAudioStream

As the QAudioOutput instance is a child of RtpAudioStream, it is also
destroyed after that. QAudioOutput's destructor somehow invokes (via
libqtmedia_pulse.so) a main loop iteration which invokes the previously
scheduled deleteLater call.

As QAudioOutput was already being destructed, this results in a crash.
Workaround this by removing this child from RtpAudioStream (no cruelty
intended).

Change-Id: I88f2e929ac566534be5d2270e2e0b194685533eb
Reviewed-on: https://code.wireshark.org/review/18970
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>

1 files changed, 3 insertions, 0 deletions

diff --git a/ui/qt/rtp_audio_stream.cpp b/ui/qt/rtp_audio_stream.cpp
index 7154d8df7a..1d8971c1d1 100644
--- a/ui/qt/rtp_audio_stream.cpp
+++ b/ui/qt/rtp_audio_stream.cpp
@@ -576,6 +576,9 @@ void RtpAudioStream::outputStateChanged(QAudio::State new_state)
     switch (new_state) {
     case QAudio::StoppedState:
         // RTP_STREAM_DEBUG("stopped %f", audio_output_->processedUSecs() / 100000.0);
+        // Detach from parent (RtpAudioStream) to prevent deleteLater from being
+        // run during destruction of this class.
+        audio_output_->setParent(0);
         audio_output_->disconnect();
         audio_output_->deleteLater();
         audio_output_ = NULL;