From: Dirk Lemstra <dirk@git.imagemagick.org>
Date: Mon, 5 Jun 2017 08:05:11 +0000 (+0200)
Subject: Added extra checks.
X-Git-Tag: 7.0.6-1~141
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=61f89f58339cac9191fe8561bf73d7e6fb0f5273;p=imagemagick

Added extra checks.
---

diff --git a/MagickCore/blob.c b/MagickCore/blob.c
index 605003758..ff96f3da6 100644
--- a/MagickCore/blob.c
+++ b/MagickCore/blob.c
@@ -3365,8 +3365,9 @@ MagickExport ssize_t ReadBlob(Image *image,const size_t length,void *data)
     }
     case CustomStream:
     {
-      count=image->blob->custom_stream->reader(q,length,
-        image->blob->custom_stream->data);
+      if (image->blob->custom_stream->reader != (CustomStreamHandler) NULL)
+        count=image->blob->custom_stream->reader(q,length,
+          image->blob->custom_stream->data);
       break;
     }
   }
@@ -5312,8 +5313,9 @@ MagickExport ssize_t WriteBlob(Image *image,const size_t length,
     }
     case CustomStream:
     {
-      count=image->blob->custom_stream->writer((const unsigned char *) data,
-        length,image->blob->custom_stream->data);
+      if (image->blob->custom_stream->writer != (CustomStreamHandler) NULL)
+        count=image->blob->custom_stream->writer((const unsigned char *) data,
+          length,image->blob->custom_stream->data);
       break;
     }
   }