From: Cfir Cohen <cfir@google.com>
To: Tom Lendacky <thomas.lendacky@amd.com>,
Gary Hook <gary.hook@amd.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
David Rientjes <rientjes@google.com>
Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
Cfir Cohen <cfir@google.com>
Subject: [PATCH] crypto: ccp/gcm - use const time tag comparison.
Date: Mon, 1 Jul 2019 17:01:32 -0700 [thread overview]
Message-ID: <20190702000132.88836-1-cfir@google.com> (raw)
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
next reply other threads:[~2019-07-02 0:02 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 0:01 Cfir Cohen [this message]
2019-07-02 0:25 ` [PATCH] crypto: ccp/gcm - use const time tag comparison Eric Biggers
2019-07-02 15:41 ` Gary R Hook
2019-07-02 15:53 ` Eric Biggers
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