Patch "sunrpc: use constant time memory comparison for mac" has been added to the 4.12-stable tree

Patch "sunrpc: use constant time memory comparison for mac" has been added to the 4.12-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    sunrpc: use constant time memory comparison for mac

to the 4.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     sunrpc-use-constant-time-memory-comparison-for-mac.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 15a8b93fd5690de017ce665382ea45e5d61811a4 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Sat, 10 Jun 2017 04:59:07 +0200
Subject: sunrpc: use constant time memory comparison for mac

From: Jason A. Donenfeld <Jason@zx2c4.com>

commit 15a8b93fd5690de017ce665382ea45e5d61811a4 upstream.

Otherwise, we enable a MAC forgery via timing attack.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Jeff Layton <jlayton@poochiereds.net>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Anna Schumaker <anna.schumaker@netapp.com>
Cc: linux-nfs@vger.kernel.org
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/sunrpc/auth_gss/gss_krb5_crypto.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/sunrpc/auth_gss/gss_krb5_crypto.c
+++ b/net/sunrpc/auth_gss/gss_krb5_crypto.c
@@ -34,6 +34,7 @@
  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */
 
+#include <crypto/algapi.h>
 #include <crypto/hash.h>
 #include <crypto/skcipher.h>
 #include <linux/err.h>
@@ -927,7 +928,7 @@ gss_krb5_aes_decrypt(struct krb5_ctx *kc
 	if (ret)
 		goto out_err;
 
-	if (memcmp(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
+	if (crypto_memneq(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
 		ret = GSS_S_BAD_SIG;
 		goto out_err;
 	}


Patches currently in stable-queue which might be from Jason@zx2c4.com are

queue-4.12/sunrpc-use-constant-time-memory-comparison-for-mac.patch
queue-4.12/bluetooth-use-constant-time-memory-comparison-for-secret-values.patch