Re: [dm-devel] [PATCH v2 10/11] crypto: ahash: Remove VLA usage for AHASH_REQUEST_ON_STACK

Kees Cook
2018-06-27T18:12:17Z

On Wed, Jun 27, 2018 at 7:34 AM, Herbert Xu <herbert@gondor.apana.org.au> wrote:
> On Tue, Jun 26, 2018 at 10:02:31AM -0700, Kees Cook wrote:
>>
>> There is no SHASH_MAX_REQSIZE?
>>
>> As for users of AHASH_REQUEST_ON_STACK, I see:
>
> These users are only using the top-level ahash interface. The
> underlying algorithms must all be shas.

typo? "shash" you mean?

I don't really understand the crypto APIs -- are you or Eric able to
help me a bit more here? I don't understand that things can wrap other
things, so I'm not sure the best way to reason about the maximum size
to choose here. (And the same for skcipher.)

-Kees

--
Kees Cook
Pixel Security