The vulnerability description explicitly names _bfd_elf_gc_mark_rsec as the affected function. The provided commit patch shows modifications to this function, as well as to _bfd_elf_section_for_symbol and bfd_elf_reloc_symbol_deleted_p. All three functions originally contained a similar pattern of accessing an array cookie->sym_hashes (or rcookie->sym_hashes) with an index calculated as r_symndx - cookie->extsymoff (or r_symndx - rcookie->extsymoff). The patch introduces a new helper function get_ext_sym_hash which includes a crucial check: && r_symndx >= cookie->extsymoff. This check prevents the out-of-bounds access that caused the heap-based buffer overflow. The removal of the direct, unguarded array access and its replacement with a call to the new, safer function in all three identified functions indicates that they were all vulnerable to this issue. The core vulnerability was the potential for r_symndx - cookie->extsymoff to be a negative or otherwise out-of-bounds index for the sym_hashes array.