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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no 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 EAA0CC43461 for ; Thu, 1 Apr 2021 06:29:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF2CC610F8 for ; Thu, 1 Apr 2021 06:29:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233149AbhDAG33 (ORCPT ); Thu, 1 Apr 2021 02:29:29 -0400 Received: from smtp.gentoo.org ([140.211.166.183]:59360 "EHLO smtp.gentoo.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229850AbhDAG25 (ORCPT ); Thu, 1 Apr 2021 02:28:57 -0400 Date: Thu, 1 Apr 2021 07:28:46 +0100 From: Sergei Trofimovich To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Oleg Nesterov , linux-ia64@vger.kernel.org, "Dmitry V . Levin" Subject: Re: [PATCH] ia64: fix user_stack_pointer() for ptrace() Message-ID: <20210401072846.0cabee26@sf> In-Reply-To: <20210331174908.4655f2a41a7b1bbec36fae47@linux-foundation.org> References: <20210331084447.2561532-1-slyfox@gentoo.org> <20210331174908.4655f2a41a7b1bbec36fae47@linux-foundation.org> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 31 Mar 2021 17:49:08 -0700 Andrew Morton wrote: > On Wed, 31 Mar 2021 09:44:47 +0100 Sergei Trofimovich wrote: > > > ia64 has two stacks: > > - memory stack (or stack), pointed at by by r12 > > - register backing store (register stack), pointed at > > ar.bsp/ar.bspstore with complications around dirty > > register frame on CPU. > > > > In https://bugs.gentoo.org/769614 Dmitry noticed that > > PTRACE_GET_SYSCALL_INFO returns register stack instead > > memory stack. > > > > The bug comes from the fact that user_stack_pointer() and > > current_user_stack_pointer() don't return the same register: > > > > ulong user_stack_pointer(struct pt_regs *regs) { return regs->ar_bspstore; } > > #define current_user_stack_pointer() (current_pt_regs()->r12) > > > > The change gets both back in sync. > > > > I think ptrace(PTRACE_GET_SYSCALL_INFO) is the only affected user > > by this bug on ia64. > > > > The change fixes 'rt_sigreturn.gen.test' strace test where > > it was observed initially. > > > > I assume a cc:stable is justified here? > > The bug seems to have been there for 10+ years, so there isn't a lot of > point in looking for the Fixes: reference. Yes, I think cc:stable is fine. -- Sergei