HTMLDOC: Stack-based buffer overflow when setting custom page output size

Buffer overflow in the set_page_size function in util.cxx in HTMLDOC 1.8.27 and earlier allows context-dependent attackers to execute arbitrary code via a long MEDIA SIZE comment. NOTE: it was later reported that there were additional vectors in htmllib.cxx and ps-pdf.cxx using an AFM font file with a long glyph name, but these vectors do not cross privilege boundaries.

HTMLDOC before 1.9.19 has an out-of-bounds write in parse_paragraph in ps-pdf.cxx because of an attempt to strip leading whitespace from a whitespace-only node.