Re: [PATCH v4 11/14] treewide: Prepare to remove VLA usage for AHASH_REQUEST_ON_STACK

On Thu, Jul 12, 2018 at 08:33:24PM -0700, Kees Cook wrote:

On Thu, Jul 12, 2018 at 5:40 PM, Herbert Xu [off-list ref] wrote:

quoted

On Thu, Jul 12, 2018 at 06:02:26PM +0200, Arnd Bergmann wrote:

quoted

Looking through some of the drivers, I found this interesting one:

As I said before these patches are fundamentally broken.  Users
of AHASH_REQUEST_ON_STACK can only use sync algorithm providers
and therefore drivers are irrelevant.

I don't understand what this means. Can you give an example of what
you want to see happen that will accomplish the VLA removals?

Any algorithm that is async must be ignored when you're calculating
the maximum on-stack size of the request.  For example, sha512-mb
is marked as async and therefore must not be used in conjunction
with AHASH_REQUEST_ON_STACK.

Cheers,
-- 
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
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