Check for valid z-transform function in shadow generation

Bug: oss-fuzz:5630
Change-Id: I608a8a2db608396932eb732b8d7b61ab9fbcc322
Reviewed-on: https://skia-review.googlesource.com/105223
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/utils/SkShadowTessellator.cpp b/src/utils/SkShadowTessellator.cpp
index 1a714076e7..11e8f2d5c6 100755
--- a/src/utils/SkShadowTessellator.cpp
+++ b/src/utils/SkShadowTessellator.cpp
@@ -384,7 +384,9 @@ SkAmbientShadowTessellator::SkAmbientShadowTessellator(const SkPath& path,
     // make sure we're not below the canvas plane
     this->setZOffset(path.getBounds(), ctm.hasPerspective());
 
-    this->setTransformedHeightFunc(ctm);
+    if (!this->setTransformedHeightFunc(ctm)) {
+        return;
+    }
 
     // Outer ring: 3*numPts
     // Middle ring: numPts
@@ -828,7 +830,9 @@ SkSpotShadowTessellator::SkSpotShadowTessellator(const SkPath& path, const SkMat
     SkMatrix fullTransform = SkMatrix::Concat(shadowTransform, ctm);
 
     // Set up our reverse mapping
-    this->setTransformedHeightFunc(fullTransform);
+    if (!this->setTransformedHeightFunc(fullTransform)) {
+        return;
+    }
 
     // TODO: calculate these reserves better
     // Penumbra ring: 3*numPts