From: Cfir Cohen <cfir@google.com>
Date: Tue, 2 Jul 2019 17:32:56 +0000 (-0700)
Subject: crypto: ccp/gcm - use const time tag comparison.
X-Git-Tag: v5.1.20~122
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bb6b587e64ac2e067d9b246e3c2ce3d1ddd712b1;p=thirdparty%2Fkernel%2Fstable.git

crypto: ccp/gcm - use const time tag comparison.

commit 538a5a072e6ef04377b180ee9b3ce5bae0a85da4 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
index 717f5551fa83e..a17de7c9841b1 100644
--- 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 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);
 	}