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=-10.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E92B7C83028 for ; Thu, 2 Sep 2021 16:54:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C848560FDC for ; Thu, 2 Sep 2021 16:54:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346411AbhIBQzw (ORCPT ); Thu, 2 Sep 2021 12:55:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234528AbhIBQzu (ORCPT ); Thu, 2 Sep 2021 12:55:50 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31DABC061575 for ; Thu, 2 Sep 2021 09:54:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=642EGsn3CAgugI9d6ee0+b40u3yojON00QOXQhzKqzc=; b=vOvAANbUzTnwWRDtlQwMjLe1x p8/xFwiZNHd3m06Kua45cHNIcAHKk1RzTHhE6z2uW1CCrBcdgXo36vtOKxz1QPOglPu7ypL+2ZI8n bX7Ri34ModPn2VBbzRwWjKg28zybAeGmJSS2EbMETvbUkl+vNMnM6U8tq+YS+8qej5g5Qk5v6ilP5 A4A4GGDWEUtxn3wGUiH21bI2JBz2WyipHHraJ7/X2FXI9zp7w3wwkqZVI0dJyD3/dddh5KX592Xmv gswVIWf57OyzOEwnqZ17CELp0nJZ5S6gE8umtdJc0+Qw/qRoE2/O2uHIK0IoOqF3d8UMvUnxwb6do ydHB6rwRA==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:48094) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mLpyT-0001hN-PU; Thu, 02 Sep 2021 17:54:01 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1mLpyM-000819-0H; Thu, 02 Sep 2021 17:53:54 +0100 Date: Thu, 2 Sep 2021 17:53:53 +0100 From: "Russell King (Oracle)" To: Keith Packard Cc: linux-kernel@vger.kernel.org, Abbott Liu , Alexander Sverdlin , Al Viro , Andrew Morton , Anshuman Khandual , Ard Biesheuvel , Arnd Bergmann , Bjorn Andersson , Florian Fainelli , Geert Uytterhoeven , Hartley Sweeten , Jens Axboe , Jian Cai , Joe Perches , Linus Walleij , linux-arm-kernel@lists.infradead.org, Maninder Singh , Manivannan Sadhasivam , Marc Zyngier , Masahiro Yamada , Mike Rapoport , Nick Desaulniers , Nick Desaulniers , Nicolas Pitre , Peter Zijlstra , Thomas Gleixner , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Valentin Schneider , Vaneet Narang , "Wolfram Sang (Renesas)" , YiFei Zhu , Keith Packard Subject: Re: [PATCH 0/2]: ARM: Enable THREAD_INFO_IN_TASK Message-ID: <20210902165353.GI22278@shell.armlinux.org.uk> References: <20210902155429.3987201-1-keithp@keithp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210902155429.3987201-1-keithp@keithp.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King (Oracle) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 02, 2021 at 08:54:26AM -0700, Keith Packard wrote: > Placing thread_info in the kernel stack leaves it vulnerable to stack > overflow attacks. This short series addresses that by using the > existing THREAD_INFO_IN_TASK infrastructure. > > As this is my first patch in this part of the kernel, I'm looking for > feedback about the general approach as well as specific comments on > places where I've missed something. > > I've only run this on armhf running under qemu, so while I've tried to > make patches for other code paths, I haven't been able to test those. > > (yes, I know checkpatch.pl complains about whitespace in asm-offsets.c, I > decided to leave the existing whitespace alone) > > Signed-off-by: Keith Packard I think you're introducing a circular dependency with this for certain kernel configurations: E.g. Have you tried running this with CONFIG_CPU_V6 enabled? +#define raw_smp_processor_id() this_cpu_read(cpu_number) +#define __smp_processor_id() __this_cpu_read(cpu_number) + +DECLARE_PER_CPU_READ_MOSTLY(unsigned int, cpu_number); this_cpu_read() is defined as: #define this_cpu_read(pcp) __pcpu_size_call_return(this_cpu_read_, pcp) (which will call this_cpu_read_4) #define this_cpu_read_4(pcp) this_cpu_generic_read(pcp) => __this_cpu_generic_read_nopreempt() => ___ret = READ_ONCE(*raw_cpu_ptr(&(pcp))); #define raw_cpu_ptr(ptr) \ ({ \ __verify_pcpu_ptr(ptr); \ arch_raw_cpu_ptr(ptr); \ }) #ifndef arch_raw_cpu_ptr #define arch_raw_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset) #endif #ifndef __my_cpu_offset #define __my_cpu_offset per_cpu_offset(raw_smp_processor_id()) #endif ... which then leads back to a use of raw_smp_processor_id(), thereby creating a circular loop of preprocessor definitions that the compiler can't resolve. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! 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Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:48094) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mLpyT-0001hN-PU; Thu, 02 Sep 2021 17:54:01 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1mLpyM-000819-0H; Thu, 02 Sep 2021 17:53:54 +0100 Date: Thu, 2 Sep 2021 17:53:53 +0100 From: "Russell King (Oracle)" To: Keith Packard Cc: linux-kernel@vger.kernel.org, Abbott Liu , Alexander Sverdlin , Al Viro , Andrew Morton , Anshuman Khandual , Ard Biesheuvel , Arnd Bergmann , Bjorn Andersson , Florian Fainelli , Geert Uytterhoeven , Hartley Sweeten , Jens Axboe , Jian Cai , Joe Perches , Linus Walleij , linux-arm-kernel@lists.infradead.org, Maninder Singh , Manivannan Sadhasivam , Marc Zyngier , Masahiro Yamada , Mike Rapoport , Nick Desaulniers , Nick Desaulniers , Nicolas Pitre , Peter Zijlstra , Thomas Gleixner , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Valentin Schneider , Vaneet Narang , "Wolfram Sang (Renesas)" , YiFei Zhu , Keith Packard Subject: Re: [PATCH 0/2]: ARM: Enable THREAD_INFO_IN_TASK Message-ID: <20210902165353.GI22278@shell.armlinux.org.uk> References: <20210902155429.3987201-1-keithp@keithp.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210902155429.3987201-1-keithp@keithp.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210902_095423_001454_39C47D70 X-CRM114-Status: GOOD ( 21.31 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Sep 02, 2021 at 08:54:26AM -0700, Keith Packard wrote: > Placing thread_info in the kernel stack leaves it vulnerable to stack > overflow attacks. This short series addresses that by using the > existing THREAD_INFO_IN_TASK infrastructure. > > As this is my first patch in this part of the kernel, I'm looking for > feedback about the general approach as well as specific comments on > places where I've missed something. > > I've only run this on armhf running under qemu, so while I've tried to > make patches for other code paths, I haven't been able to test those. > > (yes, I know checkpatch.pl complains about whitespace in asm-offsets.c, I > decided to leave the existing whitespace alone) > > Signed-off-by: Keith Packard I think you're introducing a circular dependency with this for certain kernel configurations: E.g. Have you tried running this with CONFIG_CPU_V6 enabled? +#define raw_smp_processor_id() this_cpu_read(cpu_number) +#define __smp_processor_id() __this_cpu_read(cpu_number) + +DECLARE_PER_CPU_READ_MOSTLY(unsigned int, cpu_number); this_cpu_read() is defined as: #define this_cpu_read(pcp) __pcpu_size_call_return(this_cpu_read_, pcp) (which will call this_cpu_read_4) #define this_cpu_read_4(pcp) this_cpu_generic_read(pcp) => __this_cpu_generic_read_nopreempt() => ___ret = READ_ONCE(*raw_cpu_ptr(&(pcp))); #define raw_cpu_ptr(ptr) \ ({ \ __verify_pcpu_ptr(ptr); \ arch_raw_cpu_ptr(ptr); \ }) #ifndef arch_raw_cpu_ptr #define arch_raw_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset) #endif #ifndef __my_cpu_offset #define __my_cpu_offset per_cpu_offset(raw_smp_processor_id()) #endif ... which then leads back to a use of raw_smp_processor_id(), thereby creating a circular loop of preprocessor definitions that the compiler can't resolve. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel