QtAccessibility causes crashes in several applications

[Carina Denkmann]

See backtraces, and possible further comments here:

https://bugs.kde.org/buglist.cgi?long_desc_type=substring&long_desc=QAccessible&bug_severity=crash&bug_status=UNCONFIRMED

If possible, please give instructions how to workaround it (e.g. by disabling QtAccessibility) until the bugs are fixed. If the crashes are caused by bugs in KDE applications itself, please file back bug reports to the KDE bug tracker.

---- SRU Info ----

[Impact]

QtAccessibility causes crashes in several applications when enabled. This affects Qt and KDE applications started on an accessibility-enabled desktop, be it Unity or KDE.

[Development Fix]

Upstream is confident QtAccessibility is stable enough in Qt 4.8 that no workaround will be needed in Precise.

[Stable Fix]

QtAccessibility does not cause Unity 2D to crash, as crashes are caused by widgets which are not used in Unity 2D. Since the desktop must be accessible, it is important to keep QtAccessibility activated for Unity 2D, but not for other applications.

Activation of QtAccessibility is controlled by the QT_ACCESSIBILITY environment variable.

The fix consists of two steps:

- Do not enable QtAccessibility if desktop accessibility is enabled. This is implemented in the at-spi2-core debdiff

- Enable QtAccessibility at startup of Unity 2D so that the desktop remains accessible, but disable it before starting applications so that they do not suffer from the crashes.

It is still possible for Qt application developers to test accessibility of their application by explicitly setting the QT_ACCESSIBILITY environment variable.

[Test Case]

Those crashes are difficult to reproduce, but I can reliably trigger one on my machine with Kopete.

1. Enable accessibility
2. Restart the session => the QT_ACCESSIBILITY environment variable should be set
3. Start Kopete => crash
4. Ensure unity-2d still have accessibility enabled

[Regression Potential]

This fix causes accessibility to be disabled for all Qt applications but Unity 2D. Users who have started to rely on QtAccessibility will not be able to use it anymore. We (upstream and I) believe that the current situation is worse and that QtAccessibility is not good enough in Oneiric anyway for users to rely on it yet.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[michaelcochez (michaelcochez)]

Please see also this bug report concerning a bug in qt-at-spi causing okular to crash:
https://bugs.kde.org/show_bug.cgi?id=284616

[Marcelo Escobal (marcelo-escobal)]

Workaround:
First I uninstalled kaccessible but it didn't change anything.
Then I uninstalled (purged) qt-at-spi.
It works now.

Marcelo.

[drorlev (dror-sign)]

Purging qt-qt-spi also helped running rkward under Ubuntu 11.10

Marcelo, thanks !

dror

[Aurélien Gâteau (agateau)]

Debdiff for at-spi2-core.

Note that this also add --enable-gtk-doc to the configure options. This change is unrelated to the bug but I could not build the package without it.

[Aurélien Gâteau (agateau)]

Enable QtAccessibility at startup, disable it before starting applications.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity-2d - 4.12.0-0ubuntu2

---------------
unity-2d (4.12.0-0ubuntu2) precise; urgency=low

  * Enable accessibility at startup, disable it for started applications
    (LP: #877358)
 -- Aurelien Gateau <email address hidden> Wed, 23 Nov 2011 15:05:39 +0100

[Martin Pitt (pitti)]

Hello Carina, or anyone else affected,

Accepted unity-2d into oneiric-proposed, the package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

[Aurélien Gâteau (agateau)]

The fix involves unity-2d and at-spi2-core but updating at-spi2-core before unity-2d would disable accessibility support in unity-2d. Therefore, unity-2d has been pushed first, at-spi2-core will be pushed in a few days. Until the at-spi2-core is in, the bug won't be fixed. One can however already check the unity-2d change does not cause any regression.

[Aurélien Gâteau (agateau)]

Small correction: the unity-2d fix unsets the QT_ACCESSIBILITY environment variable for applications started by unity-2d, so it will fix the bug for unity-2d users. However, the bug won't be fixed for unity-3d and KDE users until the at-spi2-core fix is in.

[Aurélien Gâteau (agateau)]

Updated debdiff for at-spi2-core to be against version 2.2.2-0ubuntu1 which is in oneiric-proposed.

[Aurélien Gâteau (agateau)]

New package fixes the problem. Tested by enabling screen reader and restarting unity-2d: unity-2d still have accessibility support but it is disabled for Qt apps.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity-2d - 4.12.0-0ubuntu1.1

---------------
unity-2d (4.12.0-0ubuntu1.1) oneiric-proposed; urgency=low

  * Enable accessibility at startup, disable it for started applications
    (LP: #877358)
 -- Aurelien Gateau <email address hidden> Wed, 23 Nov 2011 15:05:39 +0100

[Didier Roche-Tolomelli (didrocks)]

as the at-spi-core2 package i -proposed isn't confirmed yet (see bug #890491), I'm appending that changes as well.

[Clint Byrum (clint-fewbar)]

Hello Carina, or anyone else affected,

Accepted at-spi2-core into oneiric-proposed, the package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

[Dave (dv1)]

Hello.

I've got amarok crashing on me since I upgraded to oneiric. The full bug report is in the kde tracker here https://bugs.kde.org/show_bug.cgi?id=291421, and that has been confirmed as a dupliacte of https://bugs.kde.org/show_bug.cgi?id=284005, which points to here for the fix.

However, I've enabled proposed updates and installed at-spi2-core 2.2.2-0ubuntu1.1, but it doesn't fix the problem. Amarok still crashes whenever it tries to start playing something.

[Aurélien Gâteau (agateau)]

Current package in oneiric-proposed (2.2.2-0ubuntu1.1) does not install /etc/X11/Xsession.d/90qt-a11y anymore but it does not remove it if it is already installed. Attached is a new debdiff (2.2.2-0ubuntu1.2) which does take care of removing the file if it is already installed.

[Martin Pitt (pitti)]

Hello Carina, or anyone else affected,

Accepted at-spi2-core into oneiric-proposed. The package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

[Aurélien Gâteau (agateau)]

Confirming bug is fixed: QT_ACCESSIBILITY variable is no longer set when logging in.

[Launchpad Janitor (janitor)]

This bug was fixed in the package at-spi2-core - 2.2.2-0ubuntu1.2

---------------
at-spi2-core (2.2.2-0ubuntu1.2) oneiric-proposed; urgency=low

  * Actually remove 90qt-a11y if it is already installed.

at-spi2-core (2.2.2-0ubuntu1.1) oneiric-proposed; urgency=low

  * Remove 90qt-a11y: Qt accessibility is not stable enough in Oneiric to be
    enabled by default for all applications. A patch for unity-2d specifically
    enables accessibility for it so that the desktop remains accessible.
    (LP: #877358)

at-spi2-core (2.2.2-0ubuntu1) oneiric-proposed; urgency=low

  * New upstream release (LP: #890491)
    - Fix for BGO#663992: set STATE_FOCUSED for a "focus" event
    - Fix return type of org.a11y.Bus.IsEnabled property
    - Declare void functions as such
 -- Aurelien Gateau <email address hidden> Tue, 24 Jan 2012 12:34:05 +0100

[Rolf Leggewie (r0lf)]

oneiric has seen the end of its life and is no longer receiving any updates. Marking the oneiric task for this ticket as "Won't Fix".

[Steve Langasek (vorlon)]

The Precise Pangolin has reached end of life, so this bug will not be fixed for that release