From mboxrd@z Thu Jan 1 00:00:00 1970 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=-19.4 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=unavailable 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 A14D5C43619 for ; Mon, 10 May 2021 12:38:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8795761483 for ; Mon, 10 May 2021 12:38:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347649AbhEJMgm (ORCPT ); Mon, 10 May 2021 08:36:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:56146 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235318AbhEJLOR (ORCPT ); Mon, 10 May 2021 07:14:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7B0C961075; Mon, 10 May 2021 11:10:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620645056; bh=id582z2zHgIDtFnlOdn0Ci+tIXY+YTX5iV853NXKwEs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wr/Rj2Qf+4OqRlOsBMMRW9thLqW0XzyNnFiHd9JpKSOk7FTsO7OHvohq6nuvz9fEc 9BX/cDDcjnL4qUc9872GSQNz47Nl7EIX8IG/PcWiAwLE/vEkoDXgE0m7cqVZA341aK ABzqbwFdmsWo53tF7BBDbu3mmHQtACWDlS9FDa3Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Gleixner , "Peter Zijlstra (Intel)" Subject: [PATCH 5.12 332/384] Revert 337f13046ff0 ("futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op") Date: Mon, 10 May 2021 12:22:01 +0200 Message-Id: <20210510102025.735241788@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210510102014.849075526@linuxfoundation.org> References: <20210510102014.849075526@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner commit 4fbf5d6837bf81fd7a27d771358f4ee6c4f243f8 upstream. The FUTEX_WAIT operand has historically a relative timeout which means that the clock id is irrelevant as relative timeouts on CLOCK_REALTIME are not subject to wall clock changes and therefore are mapped by the kernel to CLOCK_MONOTONIC for simplicity. If a caller would set FUTEX_CLOCK_REALTIME for FUTEX_WAIT the timeout is still treated relative vs. CLOCK_MONOTONIC and then the wait arms that timeout based on CLOCK_REALTIME which is broken and obviously has never been used or even tested. Reject any attempt to use FUTEX_CLOCK_REALTIME with FUTEX_WAIT again. The desired functionality can be achieved with FUTEX_WAIT_BITSET and a FUTEX_BITSET_MATCH_ANY argument. Fixes: 337f13046ff0 ("futex: Allow FUTEX_CLOCK_REALTIME with FUTEX_WAIT op") Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210422194704.834797921@linutronix.de Signed-off-by: Greg Kroah-Hartman --- kernel/futex.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/kernel/futex.c +++ b/kernel/futex.c @@ -3711,8 +3711,7 @@ long do_futex(u32 __user *uaddr, int op, if (op & FUTEX_CLOCK_REALTIME) { flags |= FLAGS_CLOCKRT; - if (cmd != FUTEX_WAIT && cmd != FUTEX_WAIT_BITSET && \ - cmd != FUTEX_WAIT_REQUEUE_PI) + if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI) return -ENOSYS; }