ImageMagick: heap-buffer overflow in log colorspace handling

ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to version 7.1.2-1, when preparing to transform from Log to sRGB colorspaces, the logmap construction fails to handle cases where the reference-black or reference-white value is larger than 1024. This leads to corrupting memory beyond the end of the allocated logmap buffer. This issue has been patched in version 7.1.2-1.