tree ba131adc9d9ffc275d1c03419bbdc2b85082cda4
parent 68245aa6f5f832ba3066fb65050ff79ad3e5531c
author Kenneth Graunke <kenneth@whitecape.org> 1483140902 -0800
committer Kenneth Graunke <kenneth@whitecape.org> 1483141582 -0800

i965: Avoid NULL pointer dereference when transform feedback is off.

upload_3dstate_streamout can be called when there's no currently bound
transform feedback object.  In this case, we get the default object,
which has a NULL shader (previously gl_shader_program, now gl_program).

The old code did something sketchy, but which worked:

   const struct gl_transform_feedback_info *linked_xfb_info =
      &xfb_obj->shader_program->LinkedTransformFeedback;

Here, if shader_program is NULL, this would be a bogus pointer of 0x60.
But we never actually dereferenced it, so it worked out.

With Timothy's recent reworks, we actually end up dereferencing
xfb_obj->program along the way, which crashes since it's NULL.

The solution is to move this pointer initialization into the "active"
block, where we know it actually exists and won't be bogus.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99231
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>