PR22048, Incorrect .eh_frame section in libc.so

[H.J. Lu]

On Wed, Aug 30, 2017 at 8:57 PM, Alan Modra <amodra@gmail.com> wrote:
> Yep, there is definitely an incorrect .eh_frame section in libc.so.
> It has a ZERO terminator in the middle!
>
>         PR 21441
>         PR 22048
>         * elflink.c (bfd_elf_discard_info): Don't pad embedded zero
>         terminators.
>
> diff --git a/bfd/elflink.c b/bfd/elflink.c
> index ceacb37..f6f57fa 100644
> --- a/bfd/elflink.c
> +++ b/bfd/elflink.c
> @@ -13878,17 +13878,22 @@ bfd_elf_discard_info (bfd *output_bfd, struct bfd_link_info *info)
>           /* Any prior sections must pad the last FDE out to the
>              output section alignment.  Otherwise we might have zero
>              padding between sections, which would be seen as a
> -            terminator.  */
> +            terminator.  If there is a terminator in the middle of
> +            FDEs, don't increase its size as that will write bogus
> +            data of whatever was after the terminator in the input
> +            file, to the output file.  */
>           for (; i != NULL; i = i->map_tail.s)
> -           {
> -             bfd_size_type size = (i->size + eh_alignment - 1) & -eh_alignment;
> -             if (i->size != size)
> -               {
> -                 i->size = size;
> -                 changed = 1;
> -                 eh_changed = 1;
> -               }
> -           }
> +           if (i->size != 4)
> +             {
> +               bfd_size_type size
> +                 = (i->size + eh_alignment - 1) & -eh_alignment;
> +               if (i->size != size)
> +                 {
> +                   i->size = size;
> +                   changed = 1;
> +                   eh_changed = 1;
> +                 }
> +             }
>         }
>        if (eh_changed)
>         elf_link_hash_traverse (elf_hash_table (info),
>

Here is a testcase.


-- 
H.J.
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