Bug 385 - glGetString(GL_VERSION) corrupts malloc heap
Summary: glGetString(GL_VERSION) corrupts malloc heap
Alias: None
Product: xorg
Classification: Unclassified
Component: Server/General (show other bugs)
Version: unspecified
Hardware: All Linux (All)
: high normal
Assignee: Egbert Eich
QA Contact:
Depends on:
Blocks: 213
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Reported: 2004-03-29 14:36 UTC by John Dennis
Modified: 2004-03-29 15:35 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:

correct size of version string (423 bytes, patch)
2004-03-29 14:39 UTC, John Dennis
no flags Details | Splinter Review

Description John Dennis 2004-03-29 14:36:24 UTC
The following code snippet reformats the version string appending "
(GLLibraryVersion)" via a sprintf format that adds " (%s)". The code originally
added 3 to the length to account for the space, open paren, and close paren. But
it forgot to add 1 more character to account for the terminating null character
that sprintf adds at the end of the string. This meant that the __glXSprintf was
writing 1 character beyond the malloc block and was corrupting the malloc heap.
The fix is to add 4 to the malloc size rather than 3, patch will be attached.

    else if ( name == GL_VERSION ) {
	if ( atof( string ) > atof( GLServerVersion ) ) {
	    buf = __glXMalloc( __glXStrlen( string ) 
			       + __glXStrlen( GLServerVersion )
			       + 3 );
	    if ( buf == NULL ) {
		string = GLServerVersion;
	    else {
		__glXSprintf( buf, "%s (%s)", GLServerVersion, string );
		string = buf;
Comment 1 John Dennis 2004-03-29 14:39:17 UTC
Created attachment 169 [details] [review]
correct size of version string
Comment 2 Mike A. Harris 2004-03-30 00:42:31 UTC
Making this bug block bug #213, the Xorg release blocker bug.
Comment 3 Egbert Eich 2004-03-30 09:35:46 UTC

 68. Fix the GLLibraryVersion string allocation to accomodate for the
     terminating \0 character which would otherwise corrupt the malloc
     heap (Bugzilla 385, John Dennis).

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