From: Gary R Hook <ghook@amd.com>
To: Eric Biggers <ebiggers@kernel.org>, Cfir Cohen <cfir@google.com>
Cc: "Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
"Hook, Gary" <Gary.Hook@amd.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
David Rientjes <rientjes@google.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>
Subject: Re: [PATCH] crypto: ccp/gcm - use const time tag comparison.
Date: Tue, 2 Jul 2019 15:41:23 +0000 [thread overview]
Message-ID: <1eea04e4-ac19-241d-695b-61be43640509@amd.com> (raw)
In-Reply-To: <20190702002522.GA693@sol.localdomain>
On 7/1/19 7:25 PM, Eric Biggers wrote:
> 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+
Yes, it does. For clarity, does that mean you've taken care of this?
next prev parent reply other threads:[~2019-07-02 15:41 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
2019-07-02 15:41 ` Gary R Hook [this message]
2019-07-02 15:53 ` Eric Biggers
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