[Bug 1015292] [NEW] X11 crashes with seg fault when running QT5 based applications on a Pandaboard with the SGX driver

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Ricardo Salveti (rsalveti):

[Impact]
Segmentation fault at X11 where the randr code could use the randr screen private data without checking for null first. This happens when the X server is running with multiple screens, some of which are randr enabled and some of which are not. Applications making protocol requests to the non-randr screens can cause segfaults where the server touches the unset private structure.

This happened initially while running Precise on a Pandaboard, as with
the driver auto-load, it starts 2 different screens, one backed up by
the PVR SGX driver, and the other by fbdev. In this case, the issue can
easily be reproduced by running any QT5 based application, as by default
it'll try to initialize the internal structures for all screens
available at the system.

The bug can also happen on cases where the user is running one screen
with the nvidia/ati driver, and the other with fbdev (external usb video
device, for example).

[Test Case]
How to reproduce the issue, on a Pandaboard:
1) Install Precise at a Pandaboard;
2) Enable the PVR SGX driver from the "Additional Driver" screen;
1) Enable https://launchpad.net/~canonical-qt5-edgers/+archive/qt5-daily
2) Install 'snowshoe-mobile' package
3) Run snowshoe: $ PATH=/opt/qt5/bin:$PATH; snowshoe

Broken Behavior: X11 will exit with a seg fault
Fixed Behavior: The QT5 based application (snowshoe) will open without crashing X11.

[Regression Potential]
Both patches are already applied at upstream, and they are simply just checking the pointers for NULL results, which would already cause a seg fault in case of NULL value, so it's safe to be applied as SRU.

[Original Report]

While testing Qt 5 support on Ubuntu, and validating the support for
OpenGL ES2.0 with Pandaboard, I couldn't start Snowshoe (Qt 5 - webkit
based browser) as it gives a segmentation fault and also breaks the X11
server (with the pvr driver).

After a quick check with Snowball (Mali 400), it worked properly and as
expected, so this could probably be related with the current SGX driver
available for Pandaboard.

How to reproduce the issue:
1) Enable https://launchpad.net/~canonical-qt5-edgers/+archive/qt5-daily
2) Install 'snowshoe-mobile' package
3) Run snowshoe: $ PATH=/opt/qt5/bin:$PATH; snowshoe

This is with Ubuntu 12.04 with pvr-omap4 1.7.10.0.1.21-0ubuntu1 (from
archive) and also 1.7.15.0.1.57-1 from TI's PPA.

** Affects: ubuntu-omap4-extras-graphics
     Importance: Undecided
         Status: New

** Affects: pvr-omap4 (Ubuntu)
     Importance: High
         Status: Invalid

** Affects: xf86-video-omap (Ubuntu)
     Importance: High
     Assignee: Ricardo Salveti (rsalveti)
         Status: In Progress

** Affects: xorg-server (Ubuntu)
     Importance: High
     Assignee: Ricardo Salveti (rsalveti)
         Status: Fix Released

** Affects: pvr-omap4 (Ubuntu Precise)
     Importance: Undecided
         Status: New

** Affects: xf86-video-omap (Ubuntu Precise)
     Importance: Undecided
         Status: Invalid

** Affects: xorg-server (Ubuntu Precise)
     Importance: High
     Assignee: Ricardo Salveti (rsalveti)
         Status: In Progress

** Affects: pvr-omap4 (Ubuntu Quantal)
     Importance: High
         Status: Invalid

** Affects: xf86-video-omap (Ubuntu Quantal)
     Importance: High
     Assignee: Ricardo Salveti (rsalveti)
         Status: In Progress

** Affects: xorg-server (Ubuntu Quantal)
     Importance: High
     Assignee: Ricardo Salveti (rsalveti)
         Status: Fix Released

-- 
X11 crashes with seg fault when running QT5 based applications on a Pandaboard with the SGX driver
https://bugs.launchpad.net/bugs/1015292
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