Division by Zero at MagickCore/colorspace-private.h

[SuhwanSong]

Prerequisites

• I have written a descriptive issue title
• I have verified that I am using the latest version of ImageMagick
• I have searched open and closed issues to ensure it has not already been reported

Description

There are 3 division by zero at MagickCore/colorspace-private.h and outside the range bug at MagickCore/quantum.h:120.

Steps to Reproduce

poc.zip

please run a following cmd with poc file.
magick $PoC -resize 1023 -render -bordercolor "rgb(46,232,244)" tmp.cmyka

Here's UBSAN log.

MagickCore/colorspace-private.h:78:38: runtime error: division by zero
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior MagickCore/colorspace-private.h:78:38 in 
MagickCore/colorspace-private.h:79:44: runtime error: division by zero
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior MagickCore/colorspace-private.h:79:44 in 
MagickCore/colorspace-private.h:80:42: runtime error: division by zero
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior MagickCore/colorspace-private.h:80:42 in 
MagickCore/quantum.h:120:10: runtime error: -nan is outside the range of representable values of type 'unsigned char'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior MagickCore/quantum.h:120:10 in

System Configuration

• ImageMagick version:
  Version: ImageMagick 7.0.8-68 Q16 x86_64 2019-10-02 https://imagemagick.org

• Environment (Operating system, version and so on):
  Description: Ubuntu 18.04.1 LTS
  Release: 18.04
  Codename: bionic

• Additional information:
  CC=clang-6 CXX=clang++6 CFLAGS="-fsanitize=address,undefined -g" CXXFLAGS="-fsanitize=address,undefined -g" ./configure --disable-openmp

[urban-warrior]

Thanks for the problem report. We can reproduce it and will have a patch to fix it in GIT master branch @ https://github.com/ImageMagick/ImageMagick later today. The patch will be available in the beta releases of ImageMagick @ https://www.imagemagick.org/download/beta/ by sometime tomorrow.