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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 07E6BC433B4 for ; Tue, 13 Apr 2021 14:34:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E4846613B2 for ; Tue, 13 Apr 2021 14:34:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343861AbhDMOfC (ORCPT ); Tue, 13 Apr 2021 10:35:02 -0400 Received: from mail.efficios.com ([167.114.26.124]:38176 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239584AbhDMOen (ORCPT ); Tue, 13 Apr 2021 10:34:43 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 696AC338DCD; Tue, 13 Apr 2021 10:34:23 -0400 (EDT) Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id 8qyx6gKrlPMl; Tue, 13 Apr 2021 10:34:22 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 18875338DCC; Tue, 13 Apr 2021 10:34:22 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 18875338DCC DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1618324462; bh=hc8m6wpSE2+B61sL0/f4cUKx6jMuXKRnIXtHUW2VmxU=; h=Date:From:To:Message-ID:MIME-Version; b=bVeTi3jz+VX/HIEAAXDhqYkdcrJai9iyYvVXqitGKMCm9cWD0eLqtGxcWYmWHJGCu 5I9keDORpnAPrR55vBPmIRcY6dVpBGtpjQx4uts3H5uwDv9ro0op7IF1jD+1OBHu5h fHbqNbdK/icrDtmDgr8OvaOZyOOMDHzzuDXp0Orb6rnEL3lUNa4embv9IrnqdlyViL yZdciRXZIGU9C7pv532VDv2/bTvy4wnRrm7RF1e1G/+rGFjswnV0C3dzAJVxAsEfhB OnrJTgPB4uq0ui8EA1tfqbtnNbDfBejncXDpwC7YGT+5K2WMdX6UG1hizPp8igGFTD wNzwQIpmiwKoQ== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id vxF9vAXLhUX6; Tue, 13 Apr 2021 10:34:22 -0400 (EDT) Received: from mail03.efficios.com (mail03.efficios.com [167.114.26.124]) by mail.efficios.com (Postfix) with ESMTP id 0988F338E1F; Tue, 13 Apr 2021 10:34:22 -0400 (EDT) Date: Tue, 13 Apr 2021 10:34:21 -0400 (EDT) From: Mathieu Desnoyers To: Eric Dumazet Cc: Ingo Molnar , Peter Zijlstra , paulmck , Boqun Feng , Arjun Roy , linux-kernel , Eric Dumazet Message-ID: <1578770214.71411.1618324461988.JavaMail.zimbra@efficios.com> In-Reply-To: <20210413073657.2308450-3-eric.dumazet@gmail.com> References: <20210413073657.2308450-1-eric.dumazet@gmail.com> <20210413073657.2308450-3-eric.dumazet@gmail.com> Subject: Re: [PATCH 2/3] rseq: remove redundant access_ok() MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.26.124] X-Mailer: Zimbra 8.8.15_GA_3996 (ZimbraWebClient - FF87 (Linux)/8.8.15_GA_4007) Thread-Topic: rseq: remove redundant access_ok() Thread-Index: pBoSJiVP0zhPstQas4t/3NbUqJRJSA== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- On Apr 13, 2021, at 3:36 AM, Eric Dumazet eric.dumazet@gmail.com wrote: > From: Eric Dumazet > > After commit 8f2817701492 ("rseq: Use get_user/put_user rather > than __get_user/__put_user") we no longer need > an access_ok() call from __rseq_handle_notify_resume() While we are doing that, should we also remove the access_ok() check in rseq_syscall() ? It look like it can also be removed for the exact same reason outlined here. Thanks, Mathieu > > Signed-off-by: Eric Dumazet > Cc: Mathieu Desnoyers > Cc: Peter Zijlstra > Cc: "Paul E. McKenney" > Cc: Boqun Feng > Cc: Arjun Roy > Cc: Ingo Molnar > --- > kernel/rseq.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/kernel/rseq.c b/kernel/rseq.c > index > d2689ccbb132c0fc8ec0924008771e5ee1ca855e..57344f9abb43905c7dd2b6081205ff508d963e1e > 100644 > --- a/kernel/rseq.c > +++ b/kernel/rseq.c > @@ -273,8 +273,6 @@ void __rseq_handle_notify_resume(struct ksignal *ksig, > struct pt_regs *regs) > > if (unlikely(t->flags & PF_EXITING)) > return; > - if (unlikely(!access_ok(t->rseq, sizeof(*t->rseq)))) > - goto error; > ret = rseq_ip_fixup(regs); > if (unlikely(ret < 0)) > goto error; > -- > 2.31.1.295.g9ea45b61b8-goog -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com