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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS 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 19169C00319 for ; Tue, 5 Mar 2019 08:22:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DD4C320842 for ; Tue, 5 Mar 2019 08:22:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551774169; bh=Xyq8EGBEULgsSRBn/tVhdClVUK+CL2ExTD94fLkdPak=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=i94mFmfU3POsWArDLUbEpevusOVfXcsggM/9+PKBWvi8UKzTIqP/1Sqgn3GVMAlDV wEY8lD8+RjubRkJ+PXvUrwNGUV9JGiQEA1HRwp07QjFKmYjVt0F7XqypOrF2ozrtIK Lsfax4omP7cyai3qH61Ix6yOscYE1dzV5Krkr5wY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727146AbfCEIWs (ORCPT ); Tue, 5 Mar 2019 03:22:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:46512 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726995AbfCEIWr (ORCPT ); Tue, 5 Mar 2019 03:22:47 -0500 Received: from devnote (p218086-mobac01.tokyo.ocn.ne.jp [153.233.209.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C3BC9206DD; Tue, 5 Mar 2019 08:22:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551774166; bh=Xyq8EGBEULgsSRBn/tVhdClVUK+CL2ExTD94fLkdPak=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=n3J2auzM3LFuPtNXAm77yrAK/EbBlgYHNj6uZi0AOnpJBn9kGkPEG5LWkSzU9nqtM 7U8w+llYVrnH0HBq58dOK0AgaPMunB1dru06roHSNgpire1VmgsoNZJIFYJCb/wHiW BJ51cFeLl6TNgEuSeVpUQErtunewzFKGiStNGw1s= Date: Tue, 5 Mar 2019 17:22:41 +0900 From: Masami Hiramatsu To: Masami Hiramatsu Cc: Linus Torvalds , Peter Zijlstra , kernel test robot , Steven Rostedt , Shuah Khan , Linux List Kernel Mailing , Andy Lutomirski , Ingo Molnar , Andrew Morton , Changbin Du , Jann Horn , Kees Cook , Andy Lutomirski , Alexei Starovoitov , Nadav Amit , Joel Fernandes , yhs@fb.com, lkp@01.org Subject: Re: [uaccess] 780464aed0: WARNING:at_arch/x86/include/asm/uaccess.h:#strnlen_user/0x Message-Id: <20190305172241.2eef39c6ca74d09120bbbcad@kernel.org> In-Reply-To: <20190305113635.18f80ea3b1f4fca54b9d21e4@kernel.org> References: <155136980507.2968.15165201054223875356.stgit@devbox> <20190303173954.kliegojbuigqi5tn@inn2.lkp.intel.com> <20190304101434.8429ffffb17813c0e7930130@kernel.org> <20190304180610.2d4f6f08d9ad89d6abae3597@kernel.org> <20190305113635.18f80ea3b1f4fca54b9d21e4@kernel.org> X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.30; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 5 Mar 2019 11:36:35 +0900 Masami Hiramatsu wrote: > On Mon, 4 Mar 2019 10:59:22 -0800 > Linus Torvalds wrote: > > I think the better way to do this is allowing strncpy_from_user() > if some conditions are match, like > > - strncpy_from_user() will be able to copy user memory with set_fs(USER_DS) > - strncpy_from_user() can copy kernel memory with set_fs(KERNEL_DS) > - strncpy_from_user() can access unsafe memory in IRQ context if > pagefault is disabled. > > This is almost done, except for CONFIG_DEBUG_ATOMIC_SLEEP=y on x86. > > So, what about adding a condition to WARN_ON_IN_IRQ() like below > instead of introducing user_access_ok() ? > > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h > index 780f2b42c8ef..ec0f0b74c9ab 100644 > --- a/arch/x86/include/asm/uaccess.h > +++ b/arch/x86/include/asm/uaccess.h > @@ -70,7 +70,7 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un > }) > > #ifdef CONFIG_DEBUG_ATOMIC_SLEEP > -# define WARN_ON_IN_IRQ() WARN_ON_ONCE(!in_task()) > +# define WARN_ON_IN_IRQ() WARN_ON_ONCE(pagefault_disabled() && !in_task()) Oops, I meant !pagefault_disabled() && !in_task(). > #else > # define WARN_ON_IN_IRQ() > #endif > > Of course we have to move pagefault_disabled() macro in somewhere better place. And I think we don't need it. anyway the macro is referenced via linux/uaccess.h. Thank you, -- Masami Hiramatsu