Eliminate invalid write

Credit OSS Fuzz

diff --git a/MagickCore/quantum.c b/MagickCore/quantum.c
index ab70316857ff97bb945577a9be3993409d50daa6..c036a7777e92c85a4ac1719c4b83e15185966b8c 100644 (file)
--- a/MagickCore/quantum.c
+++ b/MagickCore/quantum.c
@@ -689,7 +689,7 @@ MagickExport MagickBooleanType SetQuantumDepth(const Image *image,
   if (quantum_info->pixels != (MemoryInfo **) NULL)
     DestroyQuantumPixels(quantum_info);
   quantum=(quantum_info->pad+MaxPixelChannels)*(quantum_info->depth+7)/8;
-  extent=MagickMax(image->columns,image->rows)*quantum;
+  extent=4*MagickMax(image->columns,image->rows)*quantum;
   if ((MagickMax(image->columns,image->rows) != 0) &&
       (quantum != (extent/MagickMax(image->columns,image->rows))))
     return(MagickFalse);