From patchwork Mon Mar 29 07:58:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 411616 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B882C433C1 for ; Mon, 29 Mar 2021 08:05:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E06F461932 for ; Mon, 29 Mar 2021 08:05:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232149AbhC2IEe (ORCPT ); Mon, 29 Mar 2021 04:04:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:46390 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231835AbhC2IDd (ORCPT ); Mon, 29 Mar 2021 04:03:33 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1A84E619CA; Mon, 29 Mar 2021 08:03:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1617005012; bh=WWKK9RxNWAXgPCH7HSSLdGqI22JLNNmpgwz5y6Abp2M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gw+zIS9+1jp61bDfKXikSGxhU91TZuySGQkKoTysDHbit2YfS0r/Pqjj4eYLTJgjs QtXqVMbJNc7M+aJhZaBzsQPp/BWMMavPbi7s+Knk+hEeMuVT6BObo/fpLdrlp3dZty 4RC4uelScmZ49gOvXnHrw4Ul2thIrU5LKxGfxOho= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Mateusz Nosek , Thomas Gleixner , Sasha Levin , Ben Hutchings Subject: [PATCH 4.9 48/53] futex: Fix incorrect should_fail_futex() handling Date: Mon, 29 Mar 2021 09:58:23 +0200 Message-Id: <20210329075609.096873496@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210329075607.561619583@linuxfoundation.org> References: <20210329075607.561619583@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mateusz Nosek commit 921c7ebd1337d1a46783d7e15a850e12aed2eaa0 upstream. If should_futex_fail() returns true in futex_wake_pi(), then the 'ret' variable is set to -EFAULT and then immediately overwritten. So the failure injection is non-functional. Fix it by actually leaving the function and returning -EFAULT. The Fixes tag is kinda blury because the initial commit which introduced failure injection was already sloppy, but the below mentioned commit broke it completely. [ tglx: Massaged changelog ] Fixes: 6b4f4bc9cb22 ("locking/futex: Allow low-level atomic operations to return -EAGAIN") Signed-off-by: Mateusz Nosek Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20200927000858.24219-1-mateusznosek0@gmail.com Signed-off-by: Sasha Levin Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- kernel/futex.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1605,8 +1605,10 @@ static int wake_futex_pi(u32 __user *uad */ newval = FUTEX_WAITERS | task_pid_vnr(new_owner); - if (unlikely(should_fail_futex(true))) + if (unlikely(should_fail_futex(true))) { ret = -EFAULT; + goto out_unlock; + } ret = cmpxchg_futex_value_locked(&curval, uaddr, uval, newval); if (!ret && (curval != uval)) {