It is dangerous to ignore SkRect::intersect's return value

src/effects/SkBlurMaskFilter.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBlurMaskFilter.h"
 #include "SkBlurMask.h"
@@ skipping 1166 matching lines @@
     }
 
     float sigma3 = 3 * SkScalarToFloat(xformedSigma);
 
     SkRect clipRect = SkRect::Make(clipBounds);
     SkRect srcRect(srcBounds);
 
     // Outset srcRect and clipRect by 3 * sigma, to compute affected blur area.
     srcRect.outset(sigma3, sigma3);
     clipRect.outset(sigma3, sigma3);
-    srcRect.intersect(clipRect);
+    if (!srcRect.intersect(clipRect)) {
+        srcRect.setEmpty();
+    }
     *maskRect = srcRect;
     return true;
 }
 
 bool SkBlurMaskFilterImpl::filterMaskGPU(GrTexture* src,
                                          const SkMatrix& ctm,
                                          const SkRect& maskRect,
                                          GrTexture** result,
                                          bool canOverwriteSrc) const {
     SkRect clipRect = SkRect::MakeWH(maskRect.width(), maskRect.height());
@@ skipping 67 matching lines @@
     } else {
         str->append("None");
     }
     str->append("))");
 }
 #endif
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkBlurMaskFilter)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkBlurMaskFilterImpl)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END