Author: Ritesh Khadgaray <ritesh@canonical.com>
Date:   Tue Oct 8 19:52:15 2013 +0530

    fdo bug #67484 - Corrupted CustomShape crashes Xorg (edit)
    
    If t->bottom is close to MIN_INT, removing top can wraparound, so do the check properly.

diff --git a/pixman/pixman.h b/pixman/pixman.h
index 7ff9fb5..509ba5e 100644
--- a/pixman/pixman.h
+++ b/pixman/pixman.h
@@ -1030,7 +1030,7 @@ struct pixman_triangle
 #define pixman_trapezoid_valid(t)				   \
     ((t)->left.p1.y != (t)->left.p2.y &&			   \
      (t)->right.p1.y != (t)->right.p2.y &&			   \
-     (int) ((t)->bottom - (t)->top) > 0)
+     ((t)->bottom > (t)->top))
 
 struct pixman_span_fix
 {