Bug 26121

Summary: Crash on x86-64 (but not on x86) for glLightfv w/o rendering context
Product: Mesa Reporter: Tobias Burnus <tobias.burnus>
Component: Mesa coreAssignee: mesa-dev
Status: RESOLVED NOTOURBUG QA Contact:
Severity: normal    
Priority: medium    
Version: unspecified   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:

Description Tobias Burnus 2010-01-19 08:08:25 UTC 
The problem was encountered using XCrySDen (http://www.xcrysden.org/) and appears with both mesa-libGL-devel-6.5.1-9.fc6 and Mesa-7.7-5.3.x86_64 on Linux.

The problem is that calling glLightfv without a rendering context crashes in libGL x86-64 - while libGL x86 (i686) works. There seems to be a NULL pointer check missing.

While the application should have a rendering context (I will report a bug), it probably makes still sense to add a NULL check in Mesa.


$ cat test.c
#include <GL/gl.h>

int main ()
{
GLfloat ambient[4] = {0.2, 0.2, 0.2, 1.0};
glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
return 0;
}

$ gcc test.c -lGL && ./a.out
Segmentation fault
$ gcc -m32 test.c -lGL && ./a.out
$

See also:
http://sourceforge.net/mailarchive/message.php?msg_name=4B559729.3000509%40net-b.de
http://sourceforge.net/mailarchive/message.php?msg_name=4B55D3B5.9010506%40vmware.com
Comment 1 Tobias Burnus 2010-01-19 08:41:36 UTC 
Cross-ref to the application (xcrysden) bug report:
http://www.democritos.it/pipermail/xcrysden/2010-January/000732.html
Comment 2 Ian Romanick 2010-02-19 11:40:05 UTC 
The NULL dereference happens during function dispatch.  Add a NULL check would add overhead to every single OpenGL function call.  Correct applications should not have to pay a performance penalty to prevent buggy apps from crashing.

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