From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756010AbbBQC4h (ORCPT ); Mon, 16 Feb 2015 21:56:37 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33621 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751800AbbBQBuy (ORCPT ); Mon, 16 Feb 2015 20:50:54 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Sasha Levin" , "David Howells" Date: Tue, 17 Feb 2015 01:46:53 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 142/152] KEYS: close race between key lookup and freeing In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.67-rc1 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 [bwh: Backported to 3.2: adjust indentation] Signed-off-by: Ben Hutchings --- security/keys/gc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -186,12 +186,12 @@ static noinline void key_gc_unused_key(s 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