Re: [dm-devel] [PATCH v5 05/11] crypto: ahash: Remove VLA usage

[Kees Cook]

On Tue, Jul 17, 2018 at 4:12 PM, Eric Biggers <ebiggers3@xxxxxxxxx> wrote:
> I just don't see why ahash algorithms would need such a huge maximum digest
> size.  Don't the 'ahash' algorithms all have 'shash' equivalents too?  Is there
> actually any hash algorithm, either shash or ahash, in the Linux kernel that has
> a digest size greater than 64 bytes (512 bits)?  Note that for a real
> cryptographic hash there isn't really any need for a digest size larger than
> that, since that already gives you 256-bit collision resistance; that's why
> SHA-2 and SHA-3 max out at that size.

Yup, it certainly looks that way on investigation. I'll adjust both
ahash and shash to use the same #define.

-Kees

-- 
Kees Cook
Pixel Security