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    SubjectRe: [RFC PATCH v4] akcipher: new verify API for public key algorithms
    Herbert,

    On Fri, Feb 01, 2019 at 02:26:55PM +0800, Herbert Xu wrote:
    > On Fri, Jan 25, 2019 at 09:01:16PM +0300, Vitaly Chikunov wrote:
    > >
    > > @@ -781,36 +780,17 @@ static int tpm_key_verify_signature(const struct key *key,
    > > if (!req)
    > > goto error_free_tfm;
    > >
    > > - ret = -ENOMEM;
    > > - outlen = crypto_akcipher_maxsize(tfm);
    > > - output = kmalloc(outlen, GFP_KERNEL);
    > > - if (!output)
    > > - goto error_free_req;
    > > -
    > > - sg_init_one(&sig_sg, sig->s, sig->s_size);
    > > - sg_init_one(&digest_sg, output, outlen);
    > > - akcipher_request_set_crypt(req, &sig_sg, &digest_sg, sig->s_size,
    > > - outlen);
    > > + sg_init_table(&src_sg, 2);
    > > + sg_set_buf(&src_sg[0], sig->s, sig->s_size);
    > > + sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
    > > + akcipher_request_set_crypt(req, &src_sg, NULL, sig->s_size,
    > > + sig->digest_size);
    >
    > It's not clear that sig->digest is guaranteed to be kmalloc memory.
    > In any case, it's best not to mix unrelated changes in a single
    > patch. So please keep the kmalloc on output and then copy
    > sig->digest into it and put output into the SG list.

    It is not guaranteed that sig->s will be kmalloc memory either. (Except
    we know it for sure like we know the same about sig->digest).

    You can see in public_key_signature_free() that both fields are kfree'd
    together.

    So, I don't understand why we should treat sig->digest differently than
    sig->s.

    I was just removing kmalloc'ed output as crypto_akcipher_verify() does
    not need any output anymore. So, it's not some sort of mixing unrelated
    changes, from my point of view.

    Thanks,

    >
    > Thanks,
    > --
    > Email: Herbert Xu <herbert@gondor.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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