avoid out-of-bounds read on empty ELF note name

[fr-manvi]

GetBuildId walks the notes in every SHT_NOTE section, and each note's name comes from NoteIter::Next as name_ = StrictSubstr(remaining_, 0, note.n_namesz). The n_namesz field is read straight out of the note header, so it is attacker-controlled just like the rest of the object. When a note carries n_namesz == 0 the name_ view is empty, and the very next line checks name_[name_.size() - 1] to trim a trailing NUL, so name_.size() - 1 wraps to SIZE_MAX and the operator[] reads outside the view. I hit it feeding a crafted ET_DYN with a single empty-name note; a build with libc++ hardening traps in NoteIter::Next, and it is on the default path since GetBuildId runs for every non-object input. Guarding the trim with !name_.empty() closes it while leaving the normal case (a name ending in NUL) unchanged. Added a yaml2obj regression alongside the other elf tests.

[fr-manvi]

any update?

[fr-manvi]

any update?