From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:40414 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752960AbcBNW2m (ORCPT ); Sun, 14 Feb 2016 17:28:42 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xiaofei Rex Guo , Ryan Ware , Mimi Zohar , James Morris Subject: [PATCH 4.4 104/117] EVM: Use crypto_memneq() for digest comparisons Date: Sun, 14 Feb 2016 14:22:21 -0800 Message-Id: <20160214222144.539098672@linuxfoundation.org> In-Reply-To: <20160214222141.393531627@linuxfoundation.org> References: <20160214222141.393531627@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ryan Ware commit 613317bd212c585c20796c10afe5daaa95d4b0a1 upstream. This patch fixes vulnerability CVE-2016-2085. The problem exists because the vm_verify_hmac() function includes a use of memcmp(). Unfortunately, this allows timing side channel attacks; specifically a MAC forgery complexity drop from 2^128 to 2^12. This patch changes the memcmp() to the cryptographically safe crypto_memneq(). Reported-by: Xiaofei Rex Guo Signed-off-by: Ryan Ware Signed-off-by: Mimi Zohar Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman --- security/integrity/evm/evm_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -23,6 +23,7 @@ #include #include #include +#include #include "evm.h" int evm_initialized; @@ -148,7 +149,7 @@ static enum integrity_status evm_verify_ xattr_value_len, calc.digest); if (rc) break; - rc = memcmp(xattr_data->digest, calc.digest, + rc = crypto_memneq(xattr_data->digest, calc.digest, sizeof(calc.digest)); if (rc) rc = -EINVAL;