[4.2.y-ckt stable] Patch "crypto: talitos - Fix timing leak in ESP ICV verification" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    crypto: talitos - Fix timing leak in ESP ICV verification

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt2.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 08a4178c766cd7fe48f97c802c657c19180fcc7f Mon Sep 17 00:00:00 2001
From: David Gstir <david at sigma-star.at>
Date: Sun, 15 Nov 2015 17:14:42 +0100
Subject: 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 at sigma-star.at>
Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
[ kamal: backport to 4.2-stable: context ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/crypto/talitos.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/crypto/talitos.c b/drivers/crypto/talitos.c
index 83aca95..95606c1 100644
--- a/drivers/crypto/talitos.c
+++ b/drivers/crypto/talitos.c
@@ -1025,7 +1025,7 @@ 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 -
+		err = crypto_memneq(icvdata, (char *)sg_virt(sg) + sg->length -
 			     ctx->authsize, ctx->authsize) ? -EBADMSG : 0;
 	}

--
1.9.1