Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <0f80852578436dbba7a0fce03d86c3fa2d38c571.camel@huaweicloud.com>
Subject: Re: [PATCH v2] KEYS: asymmetric: Copy sig and digest in
 public_key_verify_signature()
From:   Roberto Sassu <roberto.sassu@huaweicloud.com>
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     Eric Biggers <ebiggers@kernel.org>, dhowells@redhat.com,
        davem@davemloft.net, zohar@linux.ibm.com,
        dmitry.kasatkin@gmail.com, paul@paul-moore.com, jmorris@namei.org,
        serge@hallyn.com, linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org, keyrings@vger.kernel.org,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
        Roberto Sassu <roberto.sassu@huawei.com>,
        stable@vger.kernel.org
Date:   Mon, 19 Dec 2022 09:49:29 +0100
In-Reply-To: <Y5bxJ5UZNPzxwtoy@gondor.apana.org.au>
References: <20221209150633.1033556-1-roberto.sassu@huaweicloud.com>
         <Y5OGr59A9wo86rYY@sol.localdomain>
         <fa8a307541735ec9258353d8ccb75c20bb22aafe.camel@huaweicloud.com>
         <Y5bxJ5UZNPzxwtoy@gondor.apana.org.au>
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.36.5-0ubuntu1 
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Mon, 2022-12-12 at 17:15 +0800, Herbert Xu wrote:
> On Mon, Dec 12, 2022 at 10:07:38AM +0100, Roberto Sassu wrote:
> > The problem is a misalignment between req->src_len (set to sig->s_size
> > by akcipher_request_set_crypt()) and the length of the scatterlist (if
> > we set the latter to sig->s_size + sig->digest_size).
> > 
> > When rsa_enc() calls mpi_read_raw_from_sgl(), it passes req->src_len as
> > argument, and the latter allocates the MPI according to that. However,
> > it does parsing depending on the length of the scatterlist.
> > 
> > If there are two scatterlists, it is not a problem, there is no
> > misalignment. mpi_read_raw_from_sgl() picks the first. If there is just
> > one, mpi_read_raw_from_sgl() parses all data there.
> 
> Thanks for the explanation.  That's definitely a bug which should
> be fixed either in the RSA code or in MPI.
> 
> I'll look into it.

Hi Herbert

do you have any news on this bug?

Thanks

Roberto