From: Eric Biggers <ebiggers@kernel.org>
To: Cfir Cohen <cfir@google.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>,
Gary Hook <gary.hook@amd.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
David Rientjes <rientjes@google.com>,
linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org
Subject: Re: [PATCH] crypto: ccp/gcm - use const time tag comparison.
Date: Mon, 1 Jul 2019 17:25:22 -0700 [thread overview]
Message-ID: <20190702002522.GA693@sol.localdomain> (raw)
In-Reply-To: <20190702000132.88836-1-cfir@google.com>
On Mon, Jul 01, 2019 at 05:01:32PM -0700, Cfir Cohen wrote:
> Avoid leaking GCM tag through timing side channel.
>
> Signed-off-by: Cfir Cohen <cfir@google.com>
> ---
> drivers/crypto/ccp/ccp-ops.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
> index db8de89d990f..633670220f6c 100644
> --- a/drivers/crypto/ccp/ccp-ops.c
> +++ b/drivers/crypto/ccp/ccp-ops.c
> @@ -840,7 +840,8 @@ static int ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q,
> if (ret)
> goto e_tag;
>
> - ret = memcmp(tag.address, final_wa.address, AES_BLOCK_SIZE);
> + ret = crypto_memneq(tag.address, final_wa.address,
> + AES_BLOCK_SIZE) ? -EBADMSG : 0;
> ccp_dm_free(&tag);
> }
>
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
Looks like this needs:
Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5 CCPs")
Cc: <stable@vger.kernel.org> # v4.12+
- Eric
next prev parent reply other threads:[~2019-07-02 0:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 0:01 [PATCH] crypto: ccp/gcm - use const time tag comparison Cfir Cohen
2019-07-02 0:25 ` Eric Biggers [this message]
2019-07-02 15:41 ` Gary R Hook
2019-07-02 15:53 ` Eric Biggers
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