Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754742AbaFWNFF (ORCPT ); Mon, 23 Jun 2014 09:05:05 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:37118 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754714AbaFWNFC (ORCPT ); Mon, 23 Jun 2014 09:05:02 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Will Drewry , Kees Cook , Thomas Gleixner , Linus Torvalds , Luis Henriques Subject: [PATCH 3.11 68/93] futex-prevent-requeue-pi-on-same-futex.patch futex: Forbid uaddr == uaddr2 in futex_requeue(..., requeue_pi=1) Date: Mon, 23 Jun 2014 14:02:47 +0100 Message-Id: <1403528592-2163-69-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1403528592-2163-1-git-send-email-luis.henriques@canonical.com> References: <1403528592-2163-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.12 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner commit e9c243a5a6de0be8e584c604d353412584b592f8 upstream. If uaddr == uaddr2, then we have broken the rule of only requeueing from a non-pi futex to a pi futex with this call. If we attempt this, then dangling pointers may be left for rt_waiter resulting in an exploitable condition. This change brings futex_requeue() in line with futex_wait_requeue_pi() which performs the same check as per commit 6f7b0a2a5c0f ("futex: Forbid uaddr == uaddr2 in futex_wait_requeue_pi()") [ tglx: Compare the resulting keys as well, as uaddrs might be different depending on the mapping ] Fixes CVE-2014-3153. Reported-by: Pinkie Pie Signed-off-by: Will Drewry Signed-off-by: Kees Cook Signed-off-by: Thomas Gleixner Reviewed-by: Darren Hart Signed-off-by: Linus Torvalds Signed-off-by: Luis Henriques --- kernel/futex.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/kernel/futex.c b/kernel/futex.c index a62447d335ab..83b44e9c26c3 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1294,6 +1294,13 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, if (requeue_pi) { /* + * Requeue PI only works on two distinct uaddrs. This + * check is only valid for private futexes. See below. + */ + if (uaddr1 == uaddr2) + return -EINVAL; + + /* * requeue_pi requires a pi_state, try to allocate it now * without any locks in case it fails. */ @@ -1331,6 +1338,15 @@ retry: if (unlikely(ret != 0)) goto out_put_key1; + /* + * The check above which compares uaddrs is not sufficient for + * shared futexes. We need to compare the keys: + */ + if (requeue_pi && match_futex(&key1, &key2)) { + ret = -EINVAL; + goto out_put_keys; + } + hb1 = hash_futex(&key1); hb2 = hash_futex(&key2); @@ -2361,6 +2377,15 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags, if (ret) goto out_key2; + /* + * The check above which compares uaddrs is not sufficient for + * shared futexes. We need to compare the keys: + */ + if (match_futex(&q.key, &key2)) { + ret = -EINVAL; + goto out_put_keys; + } + /* Queue the futex_q, drop the hb lock, wait for wakeup. */ futex_wait_queue_me(hb, &q, to); -- 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/