Mesa (master): mesa: Add assert to check for null pointer dereference.

[Vinson Lee]

Module: Mesa
Branch: master
Commit: 7da9da190f44f504db13570c0cec05dffa240cae
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=7da9da190f44f504db13570c0cec05dffa240cae

Author: Vinson Lee <vlee at vmware.com>
Date:   Sun Feb 21 02:13:15 2010 -0800

mesa: Add assert to check for null pointer dereference.

---

 src/mesa/main/framebuffer.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/mesa/main/framebuffer.c b/src/mesa/main/framebuffer.c
index 065e25f..269bc9a 100644
--- a/src/mesa/main/framebuffer.c
+++ b/src/mesa/main/framebuffer.c
@@ -829,8 +829,12 @@ update_framebuffer(GLcontext *ctx, struct gl_framebuffer *fb)
 void
 _mesa_update_framebuffer(GLcontext *ctx)
 {
-   struct gl_framebuffer *drawFb = ctx->DrawBuffer;
-   struct gl_framebuffer *readFb = ctx->ReadBuffer;
+   struct gl_framebuffer *drawFb;
+   struct gl_framebuffer *readFb;
+
+   assert(ctx);
+   drawFb = ctx->DrawBuffer;
+   readFb = ctx->ReadBuffer;
 
    update_framebuffer(ctx, drawFb);
    if (readFb != drawFb)