Mesa (master): glx: Fix use after free problem

[Kristian Høgsberg]

Module: Mesa
Branch: master
Commit: 659dab6be6bc82f8a0551c30f1133e0010f04ed8
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=659dab6be6bc82f8a0551c30f1133e0010f04ed8

Author: Kristian Høgsberg <krh at bitplanet.net>
Date:   Wed Sep  8 14:51:18 2010 -0400

glx: Fix use after free problem

---

 src/glx/glxcurrent.c |   13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/glx/glxcurrent.c b/src/glx/glxcurrent.c
index 710985b..0d359f7 100644
--- a/src/glx/glxcurrent.c
+++ b/src/glx/glxcurrent.c
@@ -248,12 +248,6 @@ MakeContextCurrent(Display * dpy, GLXDrawable draw,
       oldGC->currentDrawable = None;
       oldGC->currentReadable = None;
       oldGC->thread_id = 0;
-      if (oldGC->xid == None && oldGC != gc)
-	 /* We are switching away from a context that was
-	  * previously destroyed, so we need to free the memory
-	  * for the old handle.
-	  */
-	 oldGC->vtable->destroy(oldGC);
    }
 
    if (gc) {
@@ -267,6 +261,13 @@ MakeContextCurrent(Display * dpy, GLXDrawable draw,
       __glXSetCurrentContextNull();
    }
 
+   if (oldGC != &dummyContext && oldGC->xid == None && oldGC != gc) {
+      /* We are switching away from a context that was
+       * previously destroyed, so we need to free the memory
+       * for the old handle. */
+      oldGC->vtable->destroy(oldGC);
+   }
+
    if (ret) {
       __glXGenerateError(dpy, gc, None, ret, X_GLXMakeContextCurrent);
       return GL_FALSE;