From 538a5a072e6ef04377b180ee9b3ce5bae0a85da4 Mon Sep 17 00:00:00 2001
From: Cfir Cohen <cfir@google.com>
Date: Tue, 2 Jul 2019 10:32:56 -0700
Subject: [PATCH] crypto: ccp/gcm - use const time tag comparison.
Git-commit: 538a5a072e6ef04377b180ee9b3ce5bae0a85da4
Patch-mainline: v5.3-rc1
References: bsc#1051510
Avoid leaking GCM tag through timing side channel.
Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5 CCPs")
Cc: <stable@vger.kernel.org> # v4.12+
Signed-off-by: Cfir Cohen <cfir@google.com>
Acked-by: Gary R Hook <ghook@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/crypto/ccp/ccp-ops.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/crypto/ccp/ccp-ops.c
+++ b/drivers/crypto/ccp/ccp-ops.c
@@ -853,7 +853,8 @@ static int ccp_run_aes_gcm_cmd(struct cc
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);
}