Uninteded Variable Length Array in ec-nist.c

[NIIBE Yutaka]

Thank you for your quick response.

Jussi Kivilinna <jussi.kivilinna at iki.fi> wrote:
> How about instead define arrays with wanted size and define 'wsize' with
> sizeof the array. This would avoid having macros. For example like this:
>
> index 69b05a6d..0de41e48 100644
> --- a/mpi/ec-nist.c
> +++ b/mpi/ec-nist.c
> @@ -94,9 +94,9 @@ _gcry_mpi_ec_nist192_mod (gcry_mpi_t w, mpi_ec_t ctx)
>     };
>     const mpi_limb64_t zero = LIMB_TO64(0);
>     mpi_ptr_t wp;
> -  mpi_size_t wsize = 192 / BITS_PER_MPI_LIMB64;
> -  mpi_limb64_t s[wsize + 1];
> -  mpi_limb64_t o[wsize + 1];
> +  mpi_limb64_t s[192 / BITS_PER_MPI_LIMB64 + 1];
> +  mpi_limb64_t o[sizeof(s)];
> +  const mpi_size_t wsize = DIM(s) - 1;
>     mpi_limb_t mask1;
>     mpi_limb_t mask2;
>     mpi_limb_t s_is_negative;

Looks nice with no macro definition.  I like it.

> If we want to, we can get rid of VLA in __gcry_burn_stack too.

I think that __gcry_burn_stack is OK with VLA, because it's quite
special use case and !HAVE_VLA version is available.
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