[PATCH 09/11] locale: Fix UB on add_locale_uint32_array

[Florian Weimer]

* Adhemerval Zanella Netto:

> On 20/05/25 09:49, Florian Weimer wrote:
>> * Adhemerval Zanella:
>> 
>>> The ubsan triggers:
>>>
>>> UBSAN: Undefined behaviour in programs/locfile.c:644:3 null pointer passed as argument 2, nonnull attribute declared at unknown:0:0
>>>
>>> The obstack_grow is only required if there is extra elements to be
>>> inserted (n_elems > 0).
>>> ---
>>>  locale/programs/locfile.c | 2 ++
>>>  1 file changed, 2 insertions(+)
>>>
>>> diff --git a/locale/programs/locfile.c b/locale/programs/locfile.c
>>> index b54fcbbceb..7907c949ea 100644
>>> --- a/locale/programs/locfile.c
>>> +++ b/locale/programs/locfile.c
>>> @@ -641,6 +641,8 @@ add_locale_uint32_array (struct locale_file *file,
>>>  {
>>>    align_locale_data (file, LOCFILE_ALIGN);
>>>    record_offset (file);
>>> +  if (n_elems == 0)
>>> +    return;
>>>    obstack_grow (&file->data, data, n_elems * sizeof (uint32_t));
>>>    maybe_swap_uint32_obstack (&file->data, n_elems);
>>>  }
>> 
>> We should fix the declaration of obstack_grow instead, to align with the
>> new declarations for memcpy et al.
>
> To accept lenght equal 0? It might be an option, I am not sure which is the
> best option.

Yes, use the nonnull_if_nonzero if available, or nothing otherwise.

Thanks,
Florian