Re: Segfault in objdump?

[Barret Rhoden]

Thanks a lot for the fix!

Barret


On 2013-06-03 at 13:36 Alan Modra wrote:
> Curiousity got the better of me.  The problem is triggered by
> a) Different memory layout when running objdump -S under make
> b) Trailing rubbish at the end of your .stab section
>  c01f75c8 00000000 44001801 e6a013c0 00000000  ....D...........
>  c01f75d8 44001901 e8a013c0 00000000 44001a01  D...........D...
>  c01f75e8 e9a013c0 0000                        ......          
>                    ^^^^
> c) These zeros are seen as a marker for the next compilation unit
>    (see include/aout/stab.def N_UNDF), bumping the .stabstr offset
>    (bdf/syms.c:1158).
> d) syms.c:1178 and syms.c:1247 store this offset string pointer with
>    a pointer to a previous stab.
> 
> We ought to be keeping a copy of the string pointer for use with any
> previous stab.
> 
>       * syms.c (_bfd_stab_section_find_nearest_line): Add last_str
>       var.  Use it with last_stab.
> 
> Index: bfd/syms.c
> ===================================================================
> RCS file: /cvs/src/src/bfd/syms.c,v
> retrieving revision 1.58
> diff -u -p -r1.58 syms.c
> --- bfd/syms.c        10 Jan 2013 20:03:55 -0000      1.58
> +++ bfd/syms.c        3 Jun 2013 04:01:18 -0000
> @@ -934,7 +934,7 @@ _bfd_stab_section_find_nearest_line (bfd
>    struct stab_find_info *info;
>    bfd_size_type stabsize, strsize;
>    bfd_byte *stab, *str;
> -  bfd_byte *last_stab = NULL;
> +  bfd_byte *last_stab, *last_str;
>    bfd_size_type stroff;
>    struct indexentry *indexentry;
>    char *file_name;
> @@ -1147,8 +1147,9 @@ _bfd_stab_section_find_nearest_line (bfd
>        file_name = NULL;
>        directory_name = NULL;
>        saw_fun = 1;
> +      stroff = 0;
>  
> -      for (i = 0, stroff = 0, stab = info->stabs, str = info->strs;
> +      for (i = 0, last_stab = stab = info->stabs, last_str = str =
> info->strs; i < info->indextablesize && stab < info->stabs + stabsize;
>          stab += STABSIZE)
>       {
> @@ -1174,7 +1175,7 @@ _bfd_stab_section_find_nearest_line (bfd
>               {
>                 info->indextable[i].val = bfd_get_32 (abfd,
> last_stab + VALOFF); info->indextable[i].stab = last_stab;
> -               info->indextable[i].str = str;
> +               info->indextable[i].str = last_str;
>                 info->indextable[i].directory_name =
> directory_name; info->indextable[i].file_name = file_name;
>                 info->indextable[i].function_name = NULL;
> @@ -1192,6 +1193,7 @@ _bfd_stab_section_find_nearest_line (bfd
>             else
>               {
>                 last_stab = stab;
> +               last_str = str;
>                 if (stab + STABSIZE >= info->stabs + stabsize
>                     || *(stab + STABSIZE + TYPEOFF) != (bfd_byte)
> N_SO) {
> @@ -1242,7 +1244,7 @@ _bfd_stab_section_find_nearest_line (bfd
>       {
>         info->indextable[i].val = bfd_get_32 (abfd, last_stab +
> VALOFF); info->indextable[i].stab = last_stab;
> -       info->indextable[i].str = str;
> +       info->indextable[i].str = last_str;
>         info->indextable[i].directory_name = directory_name;
>         info->indextable[i].file_name = file_name;
>         info->indextable[i].function_name = NULL;
>