ImageMagick: Heap Buffer Over-read in WaveletDenoise when processing small images

ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to versions 7.1.2-15 and 6.9.13-40, a heap buffer over-read vulnerability occurs when processing an image with small dimension using the `-wavelet-denoise` operator. Versions 7.1.2-15 and 6.9.13-40 contain a patch.