Ubuntu
xorg-server package

  1. Bug #550218
  2. Comment #28

Comment 28 for bug 550218

Revision history for this message
In , Jesse Barnes (jbarnes-virtuousgeek) wrote :

Created an attachment (id=34687)
Make sure corresponding X drawable exists before trying to use it

Looked over this some more with Kristian today. It looks like the root of the problem is that the GLX drawable we're destroying in __glXdrawableDestroy has a stale corresponding X drawable, which was destroyed in the GLX DestroyWindow hook (added by 120286aef59dabdb7c9fa762e08457e5cc8ec3a6).

That'll make the X drawable go away, but we'll be left with a pDraw pointing into freed space, probably crashing when we get to __glXdrawableDestroy for the actual GLX drawable in question.

This patch does a lookup on the X drawable ID corresponding to the GLX drawable at destruction time, and ignores it if it no longer exists. Kristian put together an alternate approach as well but it needs a little work: http://people.freedesktop.org/~krh/glx-mess.patch.

And per the last comment, DRI2 priv destruction also needs some fixing; I think it's now safe to always free the priv and clear the private wherever we call DRI2FreeDrawable, since we check everywhere we need to whether the priv still exists and so shouldn't crash.