Re: [PATCH] ld.so: Handle read-only dynamic section gracefully [BZ #28340]

[Florian Weimer <fweimer@redhat.com>]

* Siddhesh Poyarekar:

> +inline bool __attribute__ ((unused, always_inline))
> +elf_dynamic_info_needs_fixup (struct link_map *l)
> +{
> +#if __ELF_NATIVE_CLASS == 32
> +  typedef Elf32_Word d_tag_utype;
> +#elif __ELF_NATIVE_CLASS == 64
> +  typedef Elf64_Xword d_tag_utype;
> +#endif
> +
> +  if (l->l_addr == 0)
> +    return false;
> +
> +  for (ElfW(Dyn) *dyn = l->l_ld; dyn->d_tag != DT_NULL; dyn++)
> +    switch ((d_tag_utype) dyn->d_tag)
> +      {
> +      case DT_HASH:
> +      case DT_PLTGOT:
> +      case DT_STRTAB:
> +      case DT_SYMTAB:
> +# if !ELF_MACHINE_NO_RELA
> +      case DT_RELA:
> +# endif
> +# if !ELF_MACHINE_NO_REL
> +      case DT_REL:
> +# endif
> +      case DT_JMPREL:
> +      case VERSYMIDX (DT_VERSYM):
> +      case ADDRIDX (DT_GNU_HASH):
> +	return true;
> +      }
> +
> +  return false;
> +}

A valid dynamic object must have DT_STRTAB.  So I think we can assume
that all objects need fixup, and we do not need this helper function.

See figure 5.10 in
<http://www.sco.com/developers/gabi/latest/ch5.dynamic.html>.

Thanks,
Florian