linux-kernel - Re: [PATCH v4 3/3] crypto: Add Allwinner Security System crypto accelerator

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Message-ID: <20140724060054.GA6545@gondor.apana.org.au>
Date:	Thu, 24 Jul 2014 14:00:54 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	LABBE Corentin <clabbe.montjoie@...il.com>
Cc:	robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	rdunlap@...radead.org, maxime.ripard@...e-electrons.com,
	linux@....linux.org.uk, davem@...emloft.net,
	grant.likely@...aro.org, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-crypto@...r.kernel.org
Subject: Re: [PATCH v4 3/3] crypto: Add Allwinner Security System crypto
 accelerator

On Sat, Jul 12, 2014 at 02:59:13PM +0200, LABBE Corentin wrote:
>
> +/* sunxi_hash_init: initialize request context
> + * Activate the SS, and configure it for MD5 or SHA1
> + */
> +int sunxi_hash_init(struct ahash_request *areq)
> +{
> +	const char *hash_type;
> +	struct crypto_ahash *tfm = crypto_ahash_reqtfm(areq);
> +	struct sunxi_req_ctx *op = crypto_ahash_ctx(tfm);
> +
> +	mutex_lock(&ss->lock);
> +
> +	hash_type = crypto_tfm_alg_name(areq->base.tfm);
> +
> +	op->byte_count = 0;
> +	op->nbwait = 0;
> +	op->waitbuf = 0;
> +
> +	/* Enable and configure SS for MD5 or SHA1 */
> +	if (strcmp(hash_type, "sha1") == 0)
> +		op->mode = SS_OP_SHA1;
> +	else
> +		op->mode = SS_OP_MD5;
> +
> +	writel(op->mode | SS_ENABLED, ss->base + SS_CTL);
> +	return 0;

The hash driver is completely broken.  You are modifying tfm
ctx data which is shared by all users of a single tfm.  So
if two users conduct hashes in parallel they will step all
over each other.

Worse, the unpaired mutex_lock will quickly lead to dead locks.

You cannot assume that final will be called.

Cheers,
-- 
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
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