[1/2] Check IFUNC definition in unrelocated shared library [BZ #20019]

  Calling an IFUNC function defined in unrelocated shared library may
lead to segfault.  This patch issues an error message to request
relinking the shared library if it references IFUNC function defined
in the unrelocated shared library.

Tested on i686 and x86-64.  OK for master?


H.J.
---
	[BZ #20019]
	* sysdeps/i386/dl-machine.h (elf_machine_rel): Check IFUNC
	definition in unrelocated shared library.
	* sysdeps/x86_64/dl-machine.h (elf_machine_rela): Likewise.
---
 sysdeps/i386/dl-machine.h   | 18 +++++++++++++++++-
 sysdeps/x86_64/dl-machine.h | 18 +++++++++++++++++-
 2 files changed, 34 insertions(+), 2 deletions(-)
  

On 10/04/2016 02:45 PM, H.J. Lu wrote:
> Calling an IFUNC function defined in unrelocated shared library may
> lead to segfault.  This patch issues an error message to request
> relinking the shared library if it references IFUNC function defined
> in the unrelocated shared library.
> 
> Tested on i686 and x86-64.  OK for master?

This looks good to me and I've tested this on Fedora Rawhide.

I appreciate 2/2 patch that covers all the other machines to make sure that
they either work or fail the test. 

 
> H.J.
> ---
> 	[BZ #20019]
> 	* sysdeps/i386/dl-machine.h (elf_machine_rel): Check IFUNC
> 	definition in unrelocated shared library.
> 	* sysdeps/x86_64/dl-machine.h (elf_machine_rela): Likewise.
> ---
>  sysdeps/i386/dl-machine.h   | 18 +++++++++++++++++-
>  sysdeps/x86_64/dl-machine.h | 18 +++++++++++++++++-
>  2 files changed, 34 insertions(+), 2 deletions(-)
> 
> diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
> index 4e3968a..e5ad0c5 100644
> --- a/sysdeps/i386/dl-machine.h
> +++ b/sysdeps/i386/dl-machine.h
> @@ -321,7 +321,23 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc,
>  			       0)
>  	  && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
>  	  && __builtin_expect (!skip_ifunc, 1))
> -	value = ((Elf32_Addr (*) (void)) value) ();
> +	{
> +# ifndef RTLD_BOOTSTRAP
> +	  if (sym_map != map
> +	      && sym_map->l_type != lt_executable
> +	      && !sym_map->l_relocated)
> +	    {
> +	      const char *strtab
> +		= (const char *) D_PTR (map, l_info[DT_STRTAB]);
> +	      _dl_fatal_printf ("\
> +%s: Relink `%s' with `%s' for IFUNC symbol `%s'\n",
> +				RTLD_PROGNAME, map->l_name,
> +				sym_map->l_name,
> +				strtab + refsym->st_name);
> +	    }
> +# endif
> +	  value = ((Elf32_Addr (*) (void)) value) ();
> +	}
>  
>        switch (r_type)
>  	{
> diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
> index c0f0fa1..5c021dc 100644
> --- a/sysdeps/x86_64/dl-machine.h
> +++ b/sysdeps/x86_64/dl-machine.h
> @@ -331,7 +331,23 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc,
>  			       0)
>  	  && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
>  	  && __builtin_expect (!skip_ifunc, 1))
> -	value = ((ElfW(Addr) (*) (void)) value) ();
> +	{
> +# ifndef RTLD_BOOTSTRAP
> +	  if (sym_map != map
> +	      && sym_map->l_type != lt_executable
> +	      && !sym_map->l_relocated)
> +	    {
> +	      const char *strtab
> +		= (const char *) D_PTR (map, l_info[DT_STRTAB]);
> +	      _dl_fatal_printf ("\
> +%s: Relink `%s' with `%s' for IFUNC symbol `%s'\n",
> +				RTLD_PROGNAME, map->l_name,
> +				sym_map->l_name,
> +				strtab + refsym->st_name);
> +	    }
> +# endif
> +	  value = ((ElfW(Addr) (*) (void)) value) ();
> +	}
>  
>        switch (r_type)
>  	{
>