null pointer dereference in GetOpenCLCacheDirectory

[bestshow]

Here is the critical code: (in GetOpenCLCacheDirectory)

                  temp=(char*) AcquireMagickMemory(strlen(path)+1);        //326
                  CopyMagickString(temp,path,strlen(path)+1);

AcquireMagickMemory(...) may return NULL, so the following operations on the "temp" will dereference null pointer to cause memory error.

[mikayla-grace]

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.

[nohmask]

This was assigned CVE-2017-18209.