Mesa (master): i965: Avoid segfault in gen6_upload_state

[Carl Worth]

Module: Mesa
Branch: master
Commit: f5a8084692a1523f5085a88c22952566506c07de
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=f5a8084692a1523f5085a88c22952566506c07de

Author: Carl Worth <cworth at cworth.org>
Date:   Tue Feb 19 16:27:16 2013 -0800

i965: Avoid segfault in gen6_upload_state

This fixes a bug introduced in commit 258453716f001eab1288d99765213 and
triggered whenever "rb" is NULL.

Fixes at least one cause bug #59445:

	[SNB/IVB/HSW Bisected]Oglc draw-buffers2(advanced.blending.none) segfault
	https://bugs.freedesktop.org/show_bug.cgi?id=59445

(Though segfaults are still possible in that test case, but they have been
present since before commit 258453716f which is what's being fixed here.)

Reviewed-by: Eric Anholt <eric at anholt.net>

---

 src/mesa/drivers/dri/i965/gen6_cc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/gen6_cc.c b/src/mesa/drivers/dri/i965/gen6_cc.c
index d32f636..7ac5d5f 100644
--- a/src/mesa/drivers/dri/i965/gen6_cc.c
+++ b/src/mesa/drivers/dri/i965/gen6_cc.c
@@ -126,7 +126,7 @@ gen6_upload_blend_state(struct brw_context *brw)
           * not read the alpha channel, but will instead use the correct
           * implicit value for alpha.
           */
-         if (!_mesa_base_format_has_channel(rb->_BaseFormat, GL_TEXTURE_ALPHA_TYPE))
+         if (rb && !_mesa_base_format_has_channel(rb->_BaseFormat, GL_TEXTURE_ALPHA_TYPE))
          {
             srcRGB = brw_fix_xRGB_alpha(srcRGB);
             srcA = brw_fix_xRGB_alpha(srcA);