linux-kernel - Re: [PATCH] crypto: testmgr - properly mark the end of scatterlist

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Date:   Mon, 27 Jan 2020 18:40:35 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     Gilad Ben-Yossef <gilad@...yossef.com>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Ofir Drang <ofir.drang@....com>, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] crypto: testmgr - properly mark the end of scatterlist

On Mon, Jan 27, 2020 at 02:33:11PM +0200, Gilad Ben-Yossef wrote:
> The inauthentic AEAD test were using a scatterlist which
> could have a mismarked end node.
> 
> Fixes: 49763fc6b1 ("crypto: testmgr - generate inauthentic AEAD test vectors")
> Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com>
> 
> ---
>  crypto/testmgr.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/crypto/testmgr.c b/crypto/testmgr.c
> index 88f33c0efb23..6c432aecff97 100644
> --- a/crypto/testmgr.c
> +++ b/crypto/testmgr.c
> @@ -2225,6 +2225,8 @@ static void generate_aead_message(struct aead_request *req,
>  			generate_random_bytes((u8 *)vec->ptext, vec->plen);
>  			sg_set_buf(&src[i++], vec->ptext, vec->plen);
>  		}
> +		if (i)
> +			sg_mark_end(&src[(i-1)]);
>  		sg_init_one(&dst, vec->ctext, vec->alen + vec->clen);
>  		memcpy(iv, vec->iv, ivsize);
>  		aead_request_set_callback(req, 0, crypto_req_done, &wait);

As I responded in the other thread
(https://lkml.kernel.org/linux-crypto/20200128023455.GC960@sol.localdomain/),
I'm not sure this is really a bug.  There's a length passed along with the
scatterlist, and my understanding is that algorithms aren't supposed to look
beyond that length.  So the scatterlist end marker isn't really relevant.

- Eric