https://github.com/ImageMagick/ImageMagick/issues/926

diff --git a/MagickCore/blob.c b/MagickCore/blob.c
index 917fc0bdc2a04604c96389e83dd17a9223072e6e..372f47f0ec0301af16ddd62c7c0eca5c5652d265 100644 (file)
--- a/MagickCore/blob.c
+++ b/MagickCore/blob.c
@@ -2719,6 +2719,8 @@ MagickExport MagickBooleanType IsBlobSeekable(const Image *image)
       int
         status;
 
+      if (fileno(blob_info->file_info.file) == -1)
+        return(MagickFalse);
       status=fseek(blob_info->file_info.file,0,SEEK_CUR);
       return(status == -1 ? MagickFalse : MagickTrue);
     }