Re: [PATCH] ppp: mppe: Remove VLA usage

[Arnd Bergmann]

On Mon, Jul 16, 2018 at 6:05 AM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated
> VLA) by switching to shash directly and keeping the associated descriptor
> allocated with the regular state on the heap.
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@xxxxxxxxxxxxxx
>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

I had concerns at first that this approach might make it slower, but
upon reading through implementation of the shash_ahash_ implementation,
I concluded that it can only be better than before, improving both
performance and stack usage.

Acked-by: Arnd Bergmann <arnd@xxxxxxxx>