From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752577AbbJZTFf (ORCPT ); Mon, 26 Oct 2015 15:05:35 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:48536 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750790AbbJZTFd (ORCPT ); Mon, 26 Oct 2015 15:05:33 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: David Howells , Kamal Mostafa , Luis Henriques Subject: [PATCH 3.16.y-ckt 105/107] KEYS: Fix race between key destruction and finding a keyring by name Date: Mon, 26 Oct 2015 19:05:27 +0000 Message-Id: <1445886329-12035-1-git-send-email-luis.henriques@canonical.com> In-Reply-To: <1445867006-18048-1-git-send-email-luis.henriques@canonical.com> References: <1445867006-18048-1-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-ckt19 -stable review patch. If anyone has any objections, please let me know. ------------------ From: David Howells commit 94c4554ba07adbdde396748ee7ae01e86cf2d8d7 upstream. There appears to be a race between: (1) key_gc_unused_keys() which frees key->security and then calls keyring_destroy() to unlink the name from the name list (2) find_keyring_by_name() which calls key_permission(), thus accessing key->security, on a key before checking to see whether the key usage is 0 (ie. the key is dead and might be cleaned up). Fix this by calling ->destroy() before cleaning up the core key data - including key->security. Reported-by: Petr Matousek Signed-off-by: David Howells Cc: Kamal Mostafa Signed-off-by: Luis Henriques --- security/keys/gc.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/security/keys/gc.c b/security/keys/gc.c index 009d9370c8fd..38676fac7943 100644 --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -143,6 +143,10 @@ static noinline void key_gc_unused_keys(struct list_head *keys) kdebug("- %u", key->serial); key_check(key); + /* Throw away the key data */ + if (key->type->destroy) + key->type->destroy(key); + security_key_free(key); /* deal with the user's key tracking and quota */ @@ -157,10 +161,6 @@ static noinline void key_gc_unused_keys(struct list_head *keys) if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) atomic_dec(&key->user->nikeys); - /* now throw away the key memory */ - if (key->type->destroy) - key->type->destroy(key); - key_user_put(key->user); kfree(key->description);