Fix for crash on large image blur sigma values.

src/effects/SkBlurImageFilter.cpp

 /*
  * Copyright 2011 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 "SkBitmap.h"
 #include "SkBlurImageFilter.h"
 #include "SkColorPriv.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkGpuBlurUtils.h"
 #include "SkBlurImage_opts.h"
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #endif
 
+// This rather arbitrary-looking value results in a maximum box blur kernel size
+// of 1000 pixels on the raster path, which matches the WebKit and Firefox
+// implementations. Since the GPU path does not compute a box blur, putting
+// the limit on sigma ensures consistent behaviour between the GPU and
+// raster paths.
+#define MAX_SIGMA SkIntToScalar(532)
+
 SkBlurImageFilter::SkBlurImageFilter(SkReadBuffer& buffer)
   : INHERITED(1, buffer) {
     fSigma.fWidth = buffer.readScalar();
     fSigma.fHeight = buffer.readScalar();
     buffer.validate(SkScalarIsFinite(fSigma.fWidth) &&
                     SkScalarIsFinite(fSigma.fHeight) &&
                     (fSigma.fWidth >= 0) &&
                     (fSigma.fHeight >= 0));
 }
 
@@ skipping 128 matching lines @@
     }
 
     dst->setConfig(src.config(), srcBounds.width(), srcBounds.height());
     dst->getBounds(&dstBounds);
     if (!dst->allocPixels()) {
         return false;
     }
 
     SkVector sigma, localSigma = SkVector::Make(fSigma.width(), fSigma.height());
     ctx.ctm().mapVectors(&sigma, &localSigma, 1);
+    sigma.fX = SkMinScalar(sigma.fX, MAX_SIGMA);
+    sigma.fY = SkMinScalar(sigma.fY, MAX_SIGMA);
 
     int kernelSizeX, kernelSizeX3, lowOffsetX, highOffsetX;
     int kernelSizeY, kernelSizeY3, lowOffsetY, highOffsetY;
     getBox3Params(sigma.x(), &kernelSizeX, &kernelSizeX3, &lowOffsetX, &highOffsetX);
     getBox3Params(sigma.y(), &kernelSizeY, &kernelSizeY3, &lowOffsetY, &highOffsetY);
 
     if (kernelSizeX < 0 || kernelSizeY < 0) {
         return false;
     }
 
@@ skipping 79 matching lines @@
     if (getInput(0) && !getInput(0)->getInputResultGPU(proxy, src, ctx, &input, &srcOffset)) {
         return false;
     }
     SkIRect rect;
     if (!this->applyCropRect(ctx, proxy, input, &srcOffset, &rect, &input)) {
         return false;
     }
     GrTexture* source = input.getTexture();
     SkVector sigma, localSigma = SkVector::Make(fSigma.width(), fSigma.height());
     ctx.ctm().mapVectors(&sigma, &localSigma, 1);
+    sigma.fX = SkMinScalar(sigma.fX, MAX_SIGMA);
+    sigma.fY = SkMinScalar(sigma.fY, MAX_SIGMA);
     offset->fX = rect.fLeft;
     offset->fY = rect.fTop;
     rect.offset(-srcOffset);
     SkAutoTUnref<GrTexture> tex(SkGpuBlurUtils::GaussianBlur(source->getContext(),
                                                              source,
                                                              false,
                                                              SkRect::Make(rect),
                                                              true,
                                                              sigma.x(),
                                                              sigma.y()));
     WrapTexture(tex, rect.width(), rect.height(), result);
     return true;
 #else
     SkDEBUGFAIL("Should not call in GPU-less build");
     return false;
 #endif
 }