linux-kernel - Re: [BUG] crypto: export() overran state buffer on test vector

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Message-ID: <20200212185749.GA9886@Red>
Date:   Wed, 12 Feb 2020 19:57:49 +0100
From:   Corentin Labbe <clabbe.montjoie@...il.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     Eric Biggers <ebiggers@...nel.org>, davem@...emloft.net,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [BUG] crypto: export() overran state buffer on test vector

On Wed, Feb 12, 2020 at 10:06:28AM +0800, Herbert Xu wrote:
> On Tue, Feb 11, 2020 at 08:21:18PM +0100, Corentin Labbe wrote:
> > 
> > Do you mean that I should abandon ahash as a fallback ?
> 
> Perhaps switching to shash is not as straightforward because of
> SG handling.  But if you're getting problems with statesize
> perhaps at least force a sync ahash algorithm might be a good
> idea.
> 

I just found the problem, it happen with ARM CE which has a bigger state_size (sha256_ce_state) of 4bytes.

Since my driver didnt use statesize at all, I detect this on cra_init() like this:
if (algt->alg.hash.halg.statesize < crypto_ahash_statesize(op->fallback_tfm))
	algt->alg.hash.halg.statesize = crypto_ahash_statesize(op->fallback_tfm);

Regards