[PATCH, COMMITTED]: Fix seg fault in elf32.em:_after_open

[H.J. Lu]

On Fri, Aug 20, 2010 at 8:16 AM, Pedro Alves <pedro@codesourcery.com> wrote:
> On Friday 20 August 2010 16:00:30, Nick Clifton wrote:
>>   Whilst working on another bug I came across a seg-fault in the
>>   _after_open() function in elf32.em.  If the target is not an ELF
>>   binary then get_elf_backend_data will return NULL, but the code was
>>   not checking for this.  Fixed by applying the following patch.
>
> (...)
>
>>           bed = get_elf_backend_data (abfd);
>> !         if (bed == NULL)
>> !           s = NULL;
>> !         else
>> !           s = bfd_make_section_with_flags (abfd, ".eh_frame_hdr",
>> !                                            bed->dynamic_sec_flags
>> !                                            | SEC_READONLY);
>
> Is it valid to call get_elf_backend_data on a non-elf bfd at all?
>
> #define get_elf_backend_data(abfd) \
>   xvec_get_elf_backend_data ((abfd)->xvec)
>
> #define bfd_mach_o_get_backend_data(abfd) \
>  ((bfd_mach_o_backend_data*)(abfd)->xvec->backend_data)
>
> .#define coff_backend_info(abfd) \
> .  ((bfd_coff_backend_data *) (abfd)->xvec->backend_data)
>
> It appears that for other flavours, it may happen to return
> something undefined.
>
> Shouldn't that check be something like
> bfd_get_flavour (abfd) != bfd_target_elf_flavour instead?
>

I agree. The patch doesn't look right to me. Nick, if you can
provide a testcase, I will look into it.

Thanks.


-- 
H.J.