# HG changeset patch

# User Glenn Randers-Pehrson <glennrp+bmo@gmail.com>

# Date 1499262082 14400

# Node ID dea93a690fc125f70fb8688a0ff3035b96b0045e

# Parent  a42ae8447fe7a457790bf699371a1a6f3c6d4e57

Stop crash due to zero-length color_image while reading a JNG

diff -r a42ae8447fe7 -r dea93a690fc1 coders/png.c

--- a/coders/png.c	Tue Jul 04 16:33:37 2017 -0500

+++ b/coders/png.c	Wed Jul 05 09:41:22 2017 -0400

@@ -3314,12 +3314,13 @@

           if (logging)

             (void) LogMagickEvent(CoderEvent,GetMagickModule(),

-                                  "    Copying JDAT chunk data"

-                                  " to color_blob.");

-          if (color_image != (Image *)NULL)

+                                  "    Copying %lu bytes of JDAT chunk data"

+                                  " to color_blob.",length);

+          if (length && color_image != (Image *)NULL)

+          {

             (void) WriteBlob(color_image,length,(char *) chunk);

-          if (length)

             MagickFreeMemory(chunk);

+          }

           continue;

         }