Process crash via unterminated GNU long linkname

Heap-based buffer over-read in libarchive 3.7.7 and earlier allows local users to crash an archive-reading process via a crafted TAR archive. When header_gnu_longlink reads a GNU long linkname truncated before its terminator, it passes the unterminated heap buffer to archive_entry_set_link, whose string-length scan reads beyond the allocation. The vulnerable path is reached when a local process or an application using the library parses the malformed archive; the documented consequence is process termination rather than data disclosure or code execution.