Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755498AbbDII4p (ORCPT ); Thu, 9 Apr 2015 04:56:45 -0400 Received: from mail.kernel.org ([198.145.29.136]:43192 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933489AbbDII4j (ORCPT ); Thu, 9 Apr 2015 04:56:39 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sasha Levin , David Howells , Zefan Li Subject: [PATCH 3.4 134/176] KEYS: close race between key lookup and freeing Date: Thu, 9 Apr 2015 16:46:22 +0800 Message-Id: <1428569224-23820-134-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1428569028-23762-1-git-send-email-lizf@kernel.org> References: <1428569028-23762-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1856 Lines: 58 From: Sasha Levin 3.4.107-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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 [lizf: Backported to 3.4: adjust indentation] Signed-off-by: Zefan Li --- 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 a42b455..87632bd 100644 --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -188,12 +188,12 @@ static noinline void key_gc_unused_key(struct key *key) 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 -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/