Re: DWARF2 abstract origin issue

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Tue, Jul 29, 2008 at 8:16 AM, Dmitry Smirnov <divis1969@gmail.com> wrote:
> Hi,
>
> While using BFD (from binutils-2.18) for retriving debug info from ELF
> file generated by ADS 1.2 compiler, I've encountered a problem with
> DW_AT_abstract_origin processing.
> In my case, this attribute is used to refer a function using
> DW_FORM_ref_addr reference. Function find_abstract_instance_name (file
> dwarf2.c) totally ignores this and tries to use the value as is:
>  info_ptr = unit->info_ptr_unit + die_ref;

Is this the same as

http://www.sourceware.org/bugzilla/show_bug.cgi?id=3191

I am enclosing my patch here.


H.J.
---
>
> This caused BFD to crash while attempting to find a name.
>
> I had changed this function in such way:
>
> find_abstract_instance_name (struct comp_unit *unit, bfd_uint64_t
> die_ref, enum dwarf_form form)
> {
> ...
>  if(form == DW_FORM_ref_addr)
>  {
>    info_ptr = unit->stash->info_ptr_start + (int)(die_ref);
>    if(info_ptr >= unit->stash->info_ptr_end)
>    {
>      (*_bfd_error_handler) (_("Dwarf Error: reference addr is over
> limits %u."),
>          die_ref);
>    }
>  }
>  else
>  {
>    info_ptr = unit->info_ptr_unit + die_ref;
>  }
>
> Not sure this is correct fix since I've just learned DWARF2 for couple
> hours. Nevertheless, it works for me.
>
> Perhaps, it can be used in future BFD versions.
>
> Dmitry
>
> Here is the whole patch:
>
> --- dwarf2.c    2008-07-16 23:24:49.359375000 +0400
> +++ dwarf2.c    2008-07-17 00:59:54.093750000 +0400
> @@ -96,6 +96,7 @@
>
>   /* Pointer to the end of the .debug_info section memory buffer.  */
>   bfd_byte *info_ptr_end;
> +  bfd_byte *info_ptr_start;
>
>   /* Pointer to the bfd, section and address of the beginning of the
>      section.  The bfd might be different than expected because of
> @@ -1710,7 +1711,7 @@
>  }
>
>  static char *
> -find_abstract_instance_name (struct comp_unit *unit, bfd_uint64_t die_ref)
> +find_abstract_instance_name (struct comp_unit *unit, bfd_uint64_t
> die_ref, enum dwarf_form form)
>  {
>   bfd *abfd = unit->abfd;
>   bfd_byte *info_ptr;
> @@ -1721,7 +1722,12 @@
>
>   if(form == DW_FORM_ref_addr)
>   {
> -    info_ptr = unit->stash->info_ptr + die_ref;
> +    info_ptr = unit->stash->info_ptr_start + (int)(die_ref);
> +    if(info_ptr >= unit->stash->info_ptr_end)
> +    {
> +      (*_bfd_error_handler) (_("Dwarf Error: reference addr is over
> limits %u."),
> +          die_ref);
> +    }
>   }
>   else
>   {
> @@ -1753,7 +1759,7 @@
>                    name = attr.u.str;
>                  break;
>                case DW_AT_specification:
> -                 name = find_abstract_instance_name (unit, attr.u.val);
> +                 name = find_abstract_instance_name (unit, attr.u.val, attr.form);
>                  break;
>                case DW_AT_MIPS_linkage_name:
>                  name = attr.u.str;
> @@ -1915,7 +1921,7 @@
>                  break;
>
>                case DW_AT_abstract_origin:
> -                 func->name = find_abstract_instance_name (unit, attr.u.val);
> +                 func->name = find_abstract_instance_name (unit, attr.u.val, attr.form);
>                  break;
>
>                case DW_AT_name:
> @@ -2926,6 +2932,7 @@
>        goto done;
>
>       stash->info_ptr_end = stash->info_ptr;
> +      stash->info_ptr_start = stash->info_ptr;
>
>       for (msec = find_debug_info (debug_bfd, NULL);
>           msec;
>

Attachment: bfd-ref_addr-7.patch
Description: Binary data