From d326d32e24cbcda97c429d935fb869abf972a977 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Corentin=20No=C3=ABl?= <corentin.noel@collabora.com>
Date: Tue, 7 Sep 2021 17:53:41 +0200
Subject: [PATCH] glx: Prevent crashes when an extension isn't found
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Avoid a NULL-pointer dereference.

Fixes: 2c8a85b712e ("glx: Stash a copy of the XExtCodes in the glx_display")
Signed-off-by: Corentin Noël <corentin.noel@collabora.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12751>
---
 src/glx/glxext.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/glx/glxext.c b/src/glx/glxext.c
index 91d021e710e..07bb42e22fe 100644
--- a/src/glx/glxext.c
+++ b/src/glx/glxext.c
@@ -861,6 +861,7 @@ AllocAndFetchScreenConfigs(Display * dpy, struct glx_display * priv)
  _X_HIDDEN struct glx_display *
 __glXInitialize(Display * dpy)
 {
+   XExtCodes *codes;
    struct glx_display *dpyPriv, *d;
 #if defined(GLX_DIRECT_RENDERING) && !defined(GLX_USE_APPLEGL)
    Bool glx_direct, glx_accel;
@@ -883,8 +884,13 @@ __glXInitialize(Display * dpy)
    if (!dpyPriv)
       return NULL;
 
-   dpyPriv->codes = *XInitExtension(dpy, __glXExtensionName);
+   codes = XInitExtension(dpy, __glXExtensionName);
+   if (!codes) {
+      free(dpyPriv);
+      return NULL;
+   }
 
+   dpyPriv->codes = *codes;
    dpyPriv->dpy = dpy;
 
    /* This GLX implementation requires X_GLXQueryExtensionsString