Mesa (8.0): intel: Fix segfault in glXSwapBuffers with no bound context

[Ian Romanick]

Module: Mesa
Branch: 8.0
Commit: a12606cb544dfbd42a354779078a611f7808433c
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=a12606cb544dfbd42a354779078a611f7808433c

Author: Anuj Phogat <anuj.phogat at gmail.com>
Date:   Wed Jan 11 15:26:10 2012 -0800

intel: Fix segfault in glXSwapBuffers with no bound context

Calling glXSwapBuffers with no bound context causes segmentation
fault in function intelDRI2Flush. All the gl calls should be
ignored after setting the current context to null. So the contents
of framebuffer stay unchanged. But the driver should not seg fault.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44614

Reported-by: Yi Sun <yi.sun at intel.com>
Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
Tested-by: Yi Sun <yi.sun at intel.com>
(cherry picked from commit dd7220652e65a8a23e7739eeee687f3d6a865b80)

---

 src/mesa/drivers/dri/intel/intel_screen.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/mesa/drivers/dri/intel/intel_screen.c b/src/mesa/drivers/dri/intel/intel_screen.c
index b0e800b..a08f3d1 100644
--- a/src/mesa/drivers/dri/intel/intel_screen.c
+++ b/src/mesa/drivers/dri/intel/intel_screen.c
@@ -115,13 +115,15 @@ intelDRI2Flush(__DRIdrawable *drawable)
    GET_CURRENT_CONTEXT(ctx);
    struct intel_context *intel = intel_context(ctx);
 
-   if (intel->gen < 4)
-      INTEL_FIREVERTICES(intel);
+   if (intel != NULL) {
+      if (intel->gen < 4)
+	 INTEL_FIREVERTICES(intel);
 
-   intel->need_throttle = true;
+      intel->need_throttle = true;
 
-   if (intel->batch.used)
-      intel_batchbuffer_flush(intel);
+      if (intel->batch.used)
+	 intel_batchbuffer_flush(intel);
+   }
 }
 
 static const struct __DRI2flushExtensionRec intelFlushExtension = {