[PATCH] elf: Check multiple definition when defining hidden version

[H.J. Lu]

On Wed, Dec 2, 2020 at 6:51 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> When defining a hidden version from the nondefault version of the symbol,
> check if there is already a definition to avoid multiple definitions:
>
> [hjl@gnu-cfl-2 pr26978]$ gcc -o y main.o libbar.so -Wl,-R,.
> /usr/local/bin/ld: libbar.so:(*IND*+0x0): multiple definition of `foo@v1'; libbar.so:(.text+0x0): first defined here
> collect2: error: ld returned 1 exit status
> [hjl@gnu-cfl-2 pr26978]$ readelf --dyn-syms libbar.so
>
> Symbol table '.dynsym' contains 5 entries:
>    Num:    Value          Size Type    Bind   Vis      Ndx Name
>      0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
>      1: 0000000000001000     0 OBJECT  GLOBAL DEFAULT    7 foo@v1
>      2: 0000000000001001     0 OBJECT  WEAK   DEFAULT    7 foo@@v1
>      3: 0000000000001000     0 OBJECT  GLOBAL DEFAULT    7 foo_v1
>      4: 0000000000000000     0 OBJECT  GLOBAL DEFAULT  ABS v1
> [hjl@gnu-cfl-2 pr26978]$
>
> bfd/
>
>         PR ld/26978
>         * elflink.c (_bfd_elf_add_default_symbol): Check if there is
>         already a definition before defining an indirection.
>
> ld/
>
>         PR ld/26978
>         * testsuite/ld-elf/pr26978.ver: New file.
>         * testsuite/ld-elf/pr26978a.d: Likewise.
>         * testsuite/ld-elf/pr26978a.s: Likewise.
>         * testsuite/ld-elf/pr26978b.d: Likewise.
>         * testsuite/ld-elf/pr26978b.s: Likewise.
> ---
>  bfd/elflink.c                   | 13 +++++++++++++
>  ld/testsuite/ld-elf/pr26978.ver |  1 +
>  ld/testsuite/ld-elf/pr26978a.d  |  6 ++++++
>  ld/testsuite/ld-elf/pr26978a.s  |  7 +++++++
>  ld/testsuite/ld-elf/pr26978b.d  |  6 ++++++
>  ld/testsuite/ld-elf/pr26978b.s  |  6 ++++++
>  6 files changed, 39 insertions(+)
>  create mode 100644 ld/testsuite/ld-elf/pr26978.ver
>  create mode 100644 ld/testsuite/ld-elf/pr26978a.d
>  create mode 100644 ld/testsuite/ld-elf/pr26978a.s
>  create mode 100644 ld/testsuite/ld-elf/pr26978b.d
>  create mode 100644 ld/testsuite/ld-elf/pr26978b.s
>
> diff --git a/bfd/elflink.c b/bfd/elflink.c
> index 512c5044b3..65dc106656 100644
> --- a/bfd/elflink.c
> +++ b/bfd/elflink.c
> @@ -2077,6 +2077,19 @@ _bfd_elf_add_default_symbol (bfd *abfd,
>                               &type_change_ok, &size_change_ok, &matched))
>      return FALSE;
>
> +  /* Check if there is already a definition before defining an
> +     indirection.  */
> +  if ((hi->root.type == bfd_link_hash_defined
> +       || hi->root.type == bfd_link_hash_defweak)
> +      && (hi->def_regular || ELF_COMMON_DEF_P (hi)))
> +    {
> +      /* Handle a multiple definition.  */
> +      (*info->callbacks->multiple_definition) (info, &hi->root,
> +                                              abfd, sec,
> +                                              hi->root.u.def.value);
> +      return TRUE;
> +    }
> +
>    if (skip)
>      return TRUE;
>

This failed to build glibc.

-- 
H.J.