Bug 16067

Summary: [NULL dereference in VidModeGetCurrentModeline] 6.8.0 ati driver segfaults when using mplayer after a while
Product: xorg Reporter: Thierry Vignaud <thierry.vignaud>
Component: Server/GeneralAssignee: xf86-video-ati maintainers <xorg-driver-ati>
Status: RESOLVED FIXED QA Contact: Xorg Project Team <xorg-team>
Severity: major    
Priority: medium    
Version: 7.2 (2007.02)   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
0528-Correct-a-NULL-pointer-deference.patch none

Description Thierry Vignaud 2008-05-22 09:14:13 UTC 
After a while, the xorg server segfaults when using mplayer.
It "gracefully" handles this error by killing the X client.

You can find stack traces of the segfault which happens in
VidModeGetCurrentModeline() at:
 https://qa.mandriva.com/show_bug.cgi?id=40959

Here's the GDB trace:
https://qa.mandriva.com/attachment.cgi?id=9985
Comment 1 Thierry Vignaud 2008-05-22 10:47:01 UTC 
Further debugging showed that VidModeGetCurrentModeline() blindly dereferences pScrn->currentMode whithout checking if it's NULL
Comment 2 Alex Deucher 2008-05-22 10:51:27 UTC 
looks like a server issue.
Comment 3 Paulo César Pereira de Andrade 2008-05-23 10:32:40 UTC 
Created attachment 16708 [details] [review]
0528-Correct-a-NULL-pointer-deference.patch

  I will add this patch to Mandriva's X Server, but
maybe a similar patch could also be added to upstream
X Server, as it apparently fixes a crash that is caused
by hardware in the market, when running an application
that queries/uses XFree86-VidModeExtension.

  Note that the report about the X Server killing the
application and continuing running is a Mandriva only patch
http://svn.mandriva.com/cgi-bin/viewvc.cgi/packages/cooker/x11-server/current/SOURCES/0504-SAVE_CONTEXT-Mandriva-Custom-X-Server-patch.patch?revision=209187&view=markup

  Maybe a proper patch, not really to try to remediate
the problem of no edid information available, but for
consistency would be to ensure
hw/xfree86/modes/xf86Crtc.c:xf86SetScrnInfoModes()
is called at the proper place, and hopefully, this
way, both randr and the vidmode extension would work
together and not conflict.
Comment 4 Peter Hutterer 2008-05-26 23:56:14 UTC 
(In reply to comment #3)
> Created an attachment (id=16708) [details]
> 0528-Correct-a-NULL-pointer-deference.patch
> 
>   I will add this patch to Mandriva's X Server, but
> maybe a similar patch could also be added to upstream
> X Server, as it apparently fixes a crash that is caused
> by hardware in the market, when running an application
> that queries/uses XFree86-VidModeExtension.


Pushed as c8af7ce35a900ac9b898f51c1b95dabad3ba1d76. Thanks.

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