linux-kernel - RE: [PATCH v3 2/7] crypto: sun4i-ss: checking sg length is not sufficient

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Date:   Mon, 16 Nov 2020 14:54:58 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Corentin Labbe' <clabbe@...libre.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "jernej.skrabec@...l.net" <jernej.skrabec@...l.net>,
        "mripard@...nel.org" <mripard@...nel.org>,
        "wens@...e.org" <wens@...e.org>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-sunxi@...glegroups.com" <linux-sunxi@...glegroups.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH v3 2/7] crypto: sun4i-ss: checking sg length is not
 sufficient

From: Corentin Labbe
> Sent: 16 November 2020 13:54
> 
> The optimized cipher function need length multiple of 4 bytes.
> But it get sometimes odd length.
> This is due to SG data could be stored with an offset.
> 
> So the fix is to check also if the offset is aligned with 4 bytes.
> Fixes: 6298e948215f2 ("crypto: sunxi-ss - Add Allwinner Security System crypto accelerator")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Corentin Labbe <clabbe@...libre.com>
> ---
>  drivers/crypto/allwinner/sun4i-ss/sun4i-ss-cipher.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/crypto/allwinner/sun4i-ss/sun4i-ss-cipher.c b/drivers/crypto/allwinner/sun4i-
> ss/sun4i-ss-cipher.c
> index 19f1aa577ed4..4dd736ee5a4d 100644
> --- a/drivers/crypto/allwinner/sun4i-ss/sun4i-ss-cipher.c
> +++ b/drivers/crypto/allwinner/sun4i-ss/sun4i-ss-cipher.c
> @@ -186,12 +186,12 @@ static int sun4i_ss_cipher_poll(struct skcipher_request *areq)
>  	 * we can use the SS optimized function
>  	 */
>  	while (in_sg && no_chunk == 1) {
> -		if (in_sg->length % 4)
> +		if (in_sg->length % 4 || !IS_ALIGNED(in_sg->offset, sizeof(u32)))

You probably ought to do the test in a consistent manner.
Probably something that reduces to:
	((unsigned long)in_sg->offset | in_sg->length) & 3u

	David

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