linux-kernel - Re: [PATCH v2] crypto: ctr

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Date:   Fri, 23 Mar 2018 23:36:52 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Salvatore Mesoraca <s.mesoraca16@...il.com>
Cc:     linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
        linux-crypto@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Kees Cook <keescook@...omium.org>,
        Eric Biggers <ebiggers3@...il.com>
Subject: Re: [PATCH v2] crypto: ctr - avoid VLA use

On Thu, Mar 15, 2018 at 12:18:58PM +0100, Salvatore Mesoraca wrote:
>
> +#define MAX_BLOCKSIZE 16
> +
> +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> +#define MAX_ALIGNMASK 15
> +#else
> +#define MAX_ALIGNMASK 0
> +#endif
> +

Hmm, this won't work.  Just because you have efficient unaligned
access in general doesn't mean that every implementation can live
with unaligned access.  In particular, on x86 there are quite a
few implementations that require alignment or they will fault.

So please just make it 15 unconditionally.

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt