Eliminate a composite divide by zero

Credit OSS Fuzz

diff --git a/MagickCore/composite.c b/MagickCore/composite.c
index 80f230aa421e18aac08fea2cf5688dc876def670..5b860440665510c15a22b0eb8365233f7dd04148 100644 (file)
--- a/MagickCore/composite.c
+++ b/MagickCore/composite.c
@@ -1761,8 +1761,10 @@ MagickExport MagickBooleanType CompositeImage(Image *image,
                 pixel=QuantumRange*gamma*(Dca*(1.0-Sa));
                 break;
               }
-            pixel=QuantumRange*gamma*(Sa*Da-Sa*Da*MagickMin(1.0,(1.0-Dca/Da)*Sa/
-              Sca)+Sca*(1.0-Da)+Dca*(1.0-Sa));
+            pixel=0.0;
+            if ((IsNaN(Da) != MagickFalse) && (IsNaN(Sca) != MagickFalse))
+              pixel=QuantumRange*gamma*(Sa*Da-Sa*Da*MagickMin(1.0,(1.0-Dca/Da)*
+                Sa/Sca)+Sca*(1.0-Da)+Dca*(1.0-Sa));
             break;
           }
           case ColorDodgeCompositeOp: