Fixup various overflow conditions

third_party/agg23/agg_clip_liang_barsky.h

 
 //----------------------------------------------------------------------------
 // Anti-Grain Geometry - Version 2.3
 // Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
 //
 // Permission to copy, use, modify, sell and distribute this software
 // is granted provided this copyright notice appears in all copies.
 // This software is provided "as is" without express or implied
 // warranty, and with no claim as to its suitability for any purpose.
 //
 //----------------------------------------------------------------------------
 // Contact: mcseem@antigrain.com
 //          mcseemagg@yahoo.com
 //          http://www.antigrain.com
 //----------------------------------------------------------------------------
 //
 // Liang-Barsky clipping
 //
 //----------------------------------------------------------------------------
 #ifndef AGG_CLIP_LIANG_BARSKY_INCLUDED
 #define AGG_CLIP_LIANG_BARSKY_INCLUDED
 #include "agg_basics.h"
+#include "third_party/base/numerics/safe_math.h"
 namespace agg
 {
 template<class T>
 inline unsigned clipping_flags(T x, T y, const rect_base<T>& clip_box)
 {
     return  (x > clip_box.x2) |
             ((y > clip_box.y2) << 1) |
             ((x < clip_box.x1) << 2) |
             ((y < clip_box.y1) << 3);
 }
 template<class T>
 inline unsigned clip_liang_barsky(T x1, T y1, T x2, T y2,
                                   const rect_base<T>& clip_box,
                                   T* x, T* y)
 {
     const FX_FLOAT nearzero = 1e-30f;
-    FX_FLOAT deltax = (FX_FLOAT)(x2 - x1);
-    FX_FLOAT deltay = (FX_FLOAT)(y2 - y1);
+
+    pdfium::base::CheckedNumeric<FX_FLOAT> width = x2;
+    width -= x1;
+    if (!width.IsValid())
+        return 0;
+    pdfium::base::CheckedNumeric<FX_FLOAT> height = y2;
+    height -= y1;
+    if (!height.IsValid())
+        return 0;
+
+    FX_FLOAT deltax = width.ValueOrDefault(0);
+    FX_FLOAT deltay = height.ValueOrDefault(0);
     unsigned np = 0;
     if(deltax == 0) {
         deltax = (x1 > clip_box.x1) ? -nearzero : nearzero;
     }
     FX_FLOAT xin, xout;
     if(deltax > 0) {
         xin  = (FX_FLOAT)clip_box.x1;
         xout = (FX_FLOAT)clip_box.x2;
     } else {
         xin  = (FX_FLOAT)clip_box.x2;
@@ skipping 65 matching lines @@
                     }
                     ++np;
                 }
           }
         }
     }
     return np;
 }
 }
 #endif