Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751997AbdDAVgu (ORCPT ); Sat, 1 Apr 2017 17:36:50 -0400 Received: from mail-pf0-f195.google.com ([209.85.192.195]:35665 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751888AbdDAVgs (ORCPT ); Sat, 1 Apr 2017 17:36:48 -0400 From: Eric Biggers To: keyrings@vger.kernel.org Cc: David Howells , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Eric Biggers , stable@vger.kernel.org Subject: [PATCH] KEYS: fix dereferencing NULL payload with nonzero length Date: Sat, 1 Apr 2017 14:34:28 -0700 Message-Id: <20170401213428.17097-1-ebiggers3@gmail.com> X-Mailer: git-send-email 2.12.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1506 Lines: 42 From: Eric Biggers 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. Cc: stable@vger.kernel.org # 2.6.10+ Signed-off-by: Eric Biggers --- security/keys/keyctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 52c34532c785..57447cd29154 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -99,7 +99,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type, /* pull the payload in if one was supplied */ payload = NULL; - if (_payload) { + if (plen) { ret = -ENOMEM; payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN); if (!payload) { @@ -324,7 +324,7 @@ 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) -- 2.12.1