From: Cristy <urban-warrior@imagemagick.org>
Date: Thu, 31 May 2018 14:40:41 +0000 (-0400)
Subject: ...
X-Git-Tag: 7.0.7-38~8
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e111865b3a203af83334ee09ed014355530ab1b5;p=imagemagick

...
---

diff --git a/coders/png.c b/coders/png.c
index 96b9c65f0..cc9693fa4 100644
--- a/coders/png.c
+++ b/coders/png.c
@@ -4795,7 +4795,8 @@ static Image *ReadOneJNGImage(MngInfo *mng_info,
       {
         /* Copy chunk data to alpha_image->blob */
 
-        if (alpha_image != NULL && image_info->ping == MagickFalse)
+        if ((alpha_image != NULL) && (image_info->ping == MagickFalse) &&
+            (length != 0))
           {
             if (logging != MagickFalse)
               (void) LogMagickEvent(CoderEvent,GetMagickModule(),