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From:   Paul Moore <paul@paul-moore.com>
Date:   Fri, 20 Jan 2023 14:21:04 -0500
Message-ID: <CAHC9VhRSLh9y7KBCOhpvK2cwPmhyMr2dudhjcsEZ-Qmovi86Nw@mail.gmail.com>
Subject: Re: [PATCH] public_key: Add a comment to public_key_signature struct definition
To:     Roberto Sassu <roberto.sassu@huaweicloud.com>, dhowells@redhat.com
Cc:     herbert@gondor.apana.org.au, davem@davemloft.net,
        zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, jmorris@namei.org,
        serge@hallyn.com, ebiggers@kernel.org, keyrings@vger.kernel.org,
        linux-crypto@vger.kernel.org, linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Roberto Sassu <roberto.sassu@huawei.com>
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On Wed, Dec 7, 2022 at 5:55 AM Roberto Sassu
<roberto.sassu@huaweicloud.com> wrote:
>
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> public_key_verify_signature() calls sg_set_buf() to set the signature and
> digest for the signature verification.
>
> As sg_set_buf() requires the buffer to be in physically contiguous memory,
> see commit ac4e97abce9b8 ("scatterlist: sg_set_buf() argument must be in
> linear mapping"), mention that in a comment for the signature and digest
> fields of the public_key_signature structure.
>
> Link: https://lore.kernel.org/linux-integrity/Y4pIpxbjBdajymBJ@sol.localdomain/
> Suggested-by: Eric Biggers <ebiggers@kernel.org>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
>  include/crypto/public_key.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

This seems especially important considering the BUG_ON that could be triggered.

David, are you going to pick this up?

Reviewed-by: Paul Moore <paul@paul-moore.com>

> diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
> index 68f7aa2a7e55..6d623e063034 100644
> --- a/include/crypto/public_key.h
> +++ b/include/crypto/public_key.h
> @@ -37,8 +37,8 @@ extern void public_key_free(struct public_key *key);
>   */
>  struct public_key_signature {
>         struct asymmetric_key_id *auth_ids[3];
> -       u8 *s;                  /* Signature */
> -       u8 *digest;
> +       u8 *s;                  /* Signature (in physically contiguous mem) */
> +       u8 *digest;             /* Digest (in physically contiguous mem) */
>         u32 s_size;             /* Number of bytes in signature */
>         u32 digest_size;        /* Number of bytes in digest */
>         const char *pkey_algo;
> --
> 2.25.1

-- 
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