Bug 71803 – [Qt] Flash Player GTK Crash

• Component: Plug-ins
• Status: RESOLVED INVALID

[Nicholas Smith]

If you browse to any video on the BBC iPlayer (http://www.bbc.co.uk/iplayer/episode/b0175nh5/The_Choir_Military_Wives_Military_Wives/ as an example link), QtWebKit will fail to load the video (occasionally will load sound), it will then usually crash with a GTK error which GDB shows is in magazine_chain_pop_head. It appears as though GTK has created window space for the video plugin, as if you scroll it shows the bounds of the player. Occasionally when relaunching the browser it will allow you to play the last video attempted on crash, but will promptly fail for any other video.

This issue occurs in Qt versions 4.7.1-4.7.4, and also in Qt 4.8.0, so it doesn't appear to be a new issue and also occurs with Flash Player plugins 10 & 11, issue has been tested on Ubuntu 10.04, 10.10 and 11.04.

[Nicholas Smith]

Created attachment 114048 [details]
Attachment is GDB full backtrace of crashed stack

[Nicholas Smith]

Further to the initial report I've done some further testing. I've used Arora (http://code.google.com/p/arora/) which is based on QtWebKit as well, and the issue with Flash video playback on specific pages was present there, however Arora also has a ClickToFlash function which if it's enabled stops the flash plugin from being loaded with the page, if you then use click the 'Enable flash' button it'll start playing the video correctly without crashes. 

I've been told from a few people that the issue is with the Flash Player plugin, but this would seem to refute that as when the plugin is called after page load it appears to work fine.

[Nicholas Smith]

Created attachment 116349 [details]
More GDB logging on issue

Attachment contains a GDB run with a break attached to setNPWindowIfNeeded.

[Nicholas Smith]

More information:

If I run within GDB and try loading one of the Flash videos that cause issues from iPlayer it seems to run the first time, however any further attempts results in no Flash player being drawn, and WebCore::PluginClientWrapper::PluginClientWrapper is never recalled, on something like YouTube any time a new Flash Video is encountered it'll always be called.

[Nicholas Smith]

Issue now affects all video on BBC website.

Issue persists in latest beta releases of Flash Player 11 and through out the 10.x Flash Player range.

[Nicholas Smith]

Adding export G_SLICE=always-malloc before starting any Qt WebKit based browser will get the video to actually play routinely, but will cause segmentation faults fairly regularly. It appears as if the Plugin system is incorrectly managing the memory for very, very specific Flash plugin setups.

[Jocelyn Turcotte]

=== Bulk closing of Qt bugs ===

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If you believe that this is still an important QtWebKit bug, please fill a new report at https://bugreports.qt-project.org and add a link to this issue. See http://qt-project.org/wiki/ReportingBugsInQt for additional guidelines.