glx: Added missing null check in GetDrawableAttribute()

For GLX_BACK_BUFFER_AGE_EXT query added extra null check.

Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

diff --git a/src/glx/glx_pbuffer.c b/src/glx/glx_pbuffer.c
index 8f48093..231ab20 100644 (file)
--- a/src/glx/glx_pbuffer.c
+++ b/src/glx/glx_pbuffer.c
@@ -319,8 +319,8 @@ GetDrawableAttribute(Display * dpy, GLXDrawable drawable,
    pdraw = GetGLXDRIDrawable(dpy, drawable);
 
    if (attribute == GLX_BACK_BUFFER_AGE_EXT) {
-      struct glx_screen *psc = pdraw->psc;
       struct glx_context *gc = __glXGetCurrentContext();
+      struct glx_screen *psc;
 
       /* The GLX_EXT_buffer_age spec says:
        *
@@ -328,12 +328,16 @@ GetDrawableAttribute(Display * dpy, GLXDrawable drawable,
        *   the calling thread's current context a GLXBadDrawable error is
        *   generated."
        */
-      if (gc == NULL || gc->currentDpy != dpy ||
-         (gc->currentDrawable != drawable && gc->currentReadable != drawable)) {
-         __glXSendError(dpy, GLXBadDrawable, drawable, X_GLXGetDrawableAttributes, false);
+      if (pdraw == NULL || gc == NULL || gc->currentDpy != dpy ||
+         (gc->currentDrawable != drawable &&
+         gc->currentReadable != drawable)) {
+         __glXSendError(dpy, GLXBadDrawable, drawable,
+                        X_GLXGetDrawableAttributes, false);
          return 0;
       }
 
+      psc = pdraw->psc;
+
       if (psc->driScreen->getBufferAge != NULL)
          *value = psc->driScreen->getBufferAge(pdraw);