Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932791AbdFLPtb (ORCPT ); Mon, 12 Jun 2017 11:49:31 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:44780 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932366AbdFLPmP (ORCPT ); Mon, 12 Jun 2017 11:42:15 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Biggers , David Howells , James Morris Subject: [PATCH 3.18 09/45] KEYS: fix dereferencing NULL payload with nonzero length Date: Mon, 12 Jun 2017 17:26:19 +0200 Message-Id: <20170612152553.754984123@linuxfoundation.org> X-Mailer: git-send-email 2.13.1 In-Reply-To: <20170612152553.118037974@linuxfoundation.org> References: <20170612152553.118037974@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1643 Lines: 48 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers commit 5649645d725c73df4302428ee4e02c869248b4c5 upstream. sys_add_key() and the KEYCTL_UPDATE operation of sys_keyctl() allowed a NULL payload with nonzero length to be passed to the key type's ->preparse(), ->instantiate(), and/or ->update() methods. Various key types including asymmetric, cifs.idmap, cifs.spnego, and pkcs7_test did not handle this case, allowing an unprivileged user to trivially cause a NULL pointer dereference (kernel oops) if one of these key types was present. Fix it by doing the copy_from_user() when 'plen' is nonzero rather than when '_payload' is non-NULL, causing the syscall to fail with EFAULT as expected when an invalid buffer is specified. Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman --- security/keys/keyctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -99,7 +99,7 @@ SYSCALL_DEFINE5(add_key, const char __us payload = NULL; vm = false; - if (_payload) { + if (plen) { ret = -ENOMEM; payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN); if (!payload) { @@ -333,7 +333,7 @@ long keyctl_update_key(key_serial_t id, /* pull the payload in if one was supplied */ payload = NULL; - if (_payload) { + if (plen) { ret = -ENOMEM; payload = kmalloc(plen, GFP_KERNEL); if (!payload)