From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754303AbbALSbi (ORCPT ); Mon, 12 Jan 2015 13:31:38 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:58541 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755400AbbALSbR (ORCPT ); Mon, 12 Jan 2015 13:31:17 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Sasha Levin , David Howells , Moritz Muehlenhoff , Luis Henriques Subject: [PATCH 3.16.y-ckt 216/216] KEYS: close race between key lookup and freeing Date: Mon, 12 Jan 2015 18:29:54 +0000 Message-Id: <1421087394-2712-104-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1421085933-32536-1-git-send-email-luis.henriques@canonical.com> References: <1421085933-32536-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Sasha Levin commit a3a8784454692dd72e5d5d34dcdab17b4420e74c upstream. When a key is being garbage collected, it's key->user would get put before the ->destroy() callback is called, where the key is removed from it's respective tracking structures. This leaves a key hanging in a semi-invalid state which leaves a window open for a different task to try an access key->user. An example is find_keyring_by_name() which would dereference key->user for a key that is in the process of being garbage collected (where key->user was freed but ->destroy() wasn't called yet - so it's still present in the linked list). This would cause either a panic, or corrupt memory. Fixes CVE-2014-9529. Signed-off-by: Sasha Levin Signed-off-by: David Howells Cc: Moritz Muehlenhoff Signed-off-by: Luis Henriques --- security/keys/gc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/security/keys/gc.c b/security/keys/gc.c index d3222b6d7d59..009d9370c8fd 100644 --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -157,12 +157,12 @@ static noinline void key_gc_unused_keys(struct list_head *keys) if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) atomic_dec(&key->user->nikeys); - key_user_put(key->user); - /* now throw away the key memory */ if (key->type->destroy) key->type->destroy(key); + key_user_put(key->user); + kfree(key->description); #ifdef KEY_DEBUGGING -- 2.1.4