https://github.com/ImageMagick/ImageMagick/issues/876

diff --git a/MagickCore/cache.c b/MagickCore/cache.c
index 28fc33406a617ea6ccd5fd37fd600c0bec770863..8f5c84c784ed46c1a122ab97fc48877830355d72 100644 (file)
--- a/MagickCore/cache.c
+++ b/MagickCore/cache.c
@@ -3523,7 +3523,9 @@ static MagickBooleanType OpenPixelCache(Image *image,const MapMode mode,
     status=MagickFalse;
   length=number_pixels*(cache_info->number_channels*sizeof(Quantum)+
     cache_info->metacontent_extent);
-  if ((status != MagickFalse) && (length == (MagickSizeType) ((size_t) length)))
+  if ((status != MagickFalse) && 
+      (length == (MagickSizeType) ((size_t) length)) &&
+      ((cache_info->type == UndefinedCache) || (cache_info->type == MemoryCache)))
     {
       status=AcquireMagickResource(MemoryResource,cache_info->length);
       if ((cache_info->type == UndefinedCache) && (status != MagickFalse))