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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 019F0C433EF for ; Thu, 30 Sep 2021 08:46:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D22B66187A for ; Thu, 30 Sep 2021 08:46:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348199AbhI3Irw (ORCPT ); Thu, 30 Sep 2021 04:47:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348126AbhI3Irv (ORCPT ); Thu, 30 Sep 2021 04:47:51 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 817E8C06176A; Thu, 30 Sep 2021 01:46:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=8d/h8nbryP0oox/DlztyppXYQ0VJiTBHMbHxYT4g2MA=; b=BsQNPW9QuCs+taahSJyEvp3Rn5 Xb1xz8lAshcXFfFgb1EIrAvRKPwLrP7U/84MCzl60R9Rbi9wWd0eAefJiXxbDGve0K4XPGkRTzoHY 2v0iJ1ZAGnkLb7uhiqDsOfE5jl4YVXWGMmMKRXSPR1iluINri5uET20DdA+KydQq01euzTjmuJord IAkDUm/o6MN+82D5XPfqz6mWcdZb/iXx8tf5scl1SY68IcCFzzMZjZYWwk3XxG/zbmacZmVF1oBNG T/lwVlLQoF4oAJR10a03+B3+Vb8VFeYA6KGMJPaYC/rHO7huAdkuJ+sEqg5QjhG21S62pE62A1MCZ phMzpMXw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mVrby-00CeuG-9b; Thu, 30 Sep 2021 08:40:22 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 15836300252; Thu, 30 Sep 2021 10:40:12 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E0C6620831B8A; Thu, 30 Sep 2021 10:40:11 +0200 (CEST) Date: Thu, 30 Sep 2021 10:40:11 +0200 From: Peter Zijlstra To: Josh Poimboeuf Cc: Kees Cook , kernel test robot , Vito Caputo , Jann Horn , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Andrew Morton , Christian Brauner , Anand K Mistry , "Kenta.Tada@sony.com" , Alexey Gladkov , Michael =?iso-8859-1?Q?Wei=DF?= , Michal Hocko , Helge Deller , Qi Zheng , "Tobin C. Harding" , Tycho Andersen , Thomas Gleixner , Borislav Petkov , "H. Peter Anvin" , Mark Rutland , Jens Axboe , Stefan Metzmacher , Lai Jiangshan , Andy Lutomirski , Dave Hansen , "Eric W. Biederman" , Ohhoon Kwon , Kalesh Singh , YiFei Zhu , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-hardening@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v2 0/6] wchan: Fix ORC support and leaky fallback Message-ID: References: <20210929220218.691419-1-keescook@chromium.org> <20210930010157.mtn7pjyxkxokzmyh@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210930010157.mtn7pjyxkxokzmyh@treble> Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Wed, Sep 29, 2021 at 06:01:57PM -0700, Josh Poimboeuf wrote: > - Should we use a similar sched wrapper for /proc/$pid/stack to make its > raciness go away? Alternatively, can we make /stack go away? AFAICT the semantics of that are far worse in that it wants the actual kernel stack of a task, blocked or not, which is a total pain in the arse (not to mention a giant infoleak and side-channel). > - At the risk of triggering a much larger patch set, I suspect > get_wchan() can be made generic ;-) It's just a glorified wrapper > around stack_trace_save_tsk(). Done that for you :-)