Re: [PATCH] Always clear h->verinfo.verdef when overriding a dynamic definition

[Alan Modra <amodra at gmail dot com>]

On Thu, Aug 09, 2018 at 04:09:14PM -0700, H.J. Lu wrote:
> When linker defines a symbol to override a definition, which came from
> a dynamic object before, we should always clear h->verinfo.verdef so
> that the symbol won't be associated with the version information from
> the dynamic object.  This happened to the symbol "_edata" when creating
> an unversioned dynamic object linking against libQt5Core.so.5.11.1,
> which was created by gold, with 2 entries of "_edata@Qt_5" in its dynamic
> symbol table:
> 
>   4822: 00000000004e36ed     0 NOTYPE  GLOBAL DEFAULT   21 _edata@Qt_5
>   4823: 00000000004e36ed     0 NOTYPE  GLOBAL DEFAULT   21 _edata@Qt_5
> 
> Ld created the dynamic object with "_edata" in its dynamic symbol table
> which was linker defined and associated with the version information
> from libQt5Core.so.5.11.1.

How did _edata come to have version info?  A non-default versioned
_edata (with one '@') shouldn't make _edata defined.  I think we
probably have another bug here to fix.

>  When such a dynamic object was used later,
> we got
> 
> /usr/bin/ld: bin/libKF5Service.so.5.49.0: _edata: invalid version 21 (max 0)
> /usr/bin/ld: bin/libKF5Service.so.5.49.0: error adding symbols: bad value
> 
> OK for master?
> 
> H.J.
> ---
> 	PR ld/23499
> 	* elflink.c (bfd_elf_record_link_assignment): Always clear
> 	h->verinfo.verdef when overriding a dynamic definition.
> ---
>  bfd/elflink.c | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/bfd/elflink.c b/bfd/elflink.c
> index b24fb95848..02618bed8f 100644
> --- a/bfd/elflink.c
> +++ b/bfd/elflink.c
> @@ -686,13 +686,11 @@ bfd_elf_record_link_assignment (bfd *output_bfd,
>        && !h->def_regular)
>      h->root.type = bfd_link_hash_undefined;
>  
> -  /* If this symbol is not being provided by the linker script, and it is
> -     currently defined by a dynamic object, but not by a regular object,
> -     then clear out any version information because the symbol will not be
> -     associated with the dynamic object any more.  */
> -  if (!provide
> -      && h->def_dynamic
> -      && !h->def_regular)
> +  /* If this symbol is currently defined by a dynamic object, but not
> +     by a regular object, then clear out any version information because
> +     the symbol will not be associated with the dynamic object any
> +     more.  */
> +  if (h->def_dynamic && !h->def_regular)
>      h->verinfo.verdef = NULL;
>  
>    /* Make sure this symbol is not garbage collected.  */
> -- 
> 2.17.1

-- 
Alan Modra
Australia Development Lab, IBM