From: David Gstir <david@sigma-star.at>
Date: Sun, 15 Nov 2015 16:14:42 +0000 (+0100)
Subject: crypto: talitos - Fix timing leak in ESP ICV verification
X-Git-Tag: v3.16.35~844
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=20422a48839b1c869f014f7649cd1522c968d793;p=thirdparty%2Fkernel%2Fstable.git

crypto: talitos - Fix timing leak in ESP ICV verification

commit 79960943fdc114fd4583c9ab164b5c89da7aa601 upstream.

Using non-constant time memcmp() makes the verification of the authentication
tag in the decrypt path vulnerable to timing attacks. Fix this by using
crypto_memneq() instead.

Signed-off-by: David Gstir <david@sigma-star.at>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---

diff --git a/drivers/crypto/talitos.c b/drivers/crypto/talitos.c
index 307931528eb20..da328ed633fb5 100644
--- a/drivers/crypto/talitos.c
+++ b/drivers/crypto/talitos.c
@@ -870,8 +870,8 @@ static void ipsec_esp_decrypt_swauth_done(struct device *dev,
 			icvdata = &edesc->link_tbl[0];
 
 		sg = sg_last(req->dst, edesc->dst_nents ? : 1);
-		err = memcmp(icvdata, (char *)sg_virt(sg) + sg->length -
-			     ctx->authsize, ctx->authsize) ? -EBADMSG : 0;
+		err = crypto_memneq(icvdata, (char *)sg_virt(sg) + sg->length -
+				    ctx->authsize, ctx->authsize) ? -EBADMSG : 0;
 	}
 
 	kfree(edesc);