CVE-2020-25667 — Heap-based Buffer Overflow in Imagemagick

TIFFGetProfiles() in /coders/tiff.c calls strstr() which causes a large out-of-bounds read when it searches for `"dc:format=\"image/dng\"` within `profile` due to improper string handling, when a crafted input file is provided to ImageMagick. The patch uses a StringInfo type instead of a raw C string to remedy this. This could cause an impact to availability of the application. This flaw affects ImageMagick versions prior to 7.0.9-0.