From 2274f23e6029348a5baeb6d785b0e01ac35a52da Mon Sep 17 00:00:00 2001
From: "Enrico Weigelt, metux IT consult" <info@metux.net>
Date: Tue, 6 May 2025 14:36:57 +0200
Subject: [PATCH] glx: NULL-protect validGlxFBConfigForWindow()
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If this ever happens, we clearly have a bug, so print out proper warning,
instead of silently crashing the Xserver.

| ../glx/glxcmds.c: In function ‘validGlxFBConfigForWindow’:
| ../glx/glxcmds.c:127:16: warning: dereference of NULL ‘pVisual’ [CWE-476] [-Wanalyzer-null-dereference]
|   127 |     if (pVisual->class != glxConvertToXVisualType(config->visualType) ||
|       |         ~~~~~~~^~~~~~~

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
 glx/glxcmds.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/glx/glxcmds.c b/glx/glxcmds.c
index f8c3a965c..54d6d7924 100644
--- a/glx/glxcmds.c
+++ b/glx/glxcmds.c
@@ -36,6 +36,7 @@
 #include <X11/extensions/presenttokens.h>
 
 #include "dix/dix_priv.h"
+#include "os/bug_priv.h"
 
 #include "glxserver.h"
 #include <unpack.h>
@@ -122,6 +123,8 @@ validGlxFBConfigForWindow(ClientPtr client, __GLXconfig * config,
         }
     }
 
+    BUG_RETURN_VAL(!pVisual, FALSE);
+
     /* FIXME: What exactly should we check here... */
     if (pVisual->class != glxConvertToXVisualType(config->visualType) ||
         !(config->drawableType & GLX_WINDOW_BIT)) {