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=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,URIBL_BLOCKED,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 C17BDC433EF for ; Wed, 15 Sep 2021 01:59:19 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3C44E61221 for ; Wed, 15 Sep 2021 01:59:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3C44E61221 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/zmk1GZWBuEcPjODi6PPhjH4F7ZvaKidHglDyAVK4Xc=; b=qhL8SSnV9um0cDt8xP7i9+BgaM L9KKRwUe9nq96WceniDiuGSRdJMw0J8nuEL4XqHdqIjB/tDAsoqWOg3a5WjJbfo1F/tL8E+m3Z5MD Tn9iZ7lqHaxlPCPkbYN8oUJ0IxKSLFvpqCjEHZDJqnyGNQqa8YbrEHSRMJWYaa79DEE8ujo+vB89S tMm5Vl3a2b10D8GQfhlMfHNKlTZ7aYysMcwRL6KPFWMxlttXvVj4mWTFx3kq56Nq16c9OPGpQCvQU 5pygYK9wIIUhVQTZjJLLzvrxaLbXliYF7TQgLa14Rr8ghk3NcdQX7VB5QZsOh0mqh7Eor+TWE0Nmh IGyocn+A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mQKAp-007sKU-Cm; Wed, 15 Sep 2021 01:57:19 +0000 Received: from out30-131.freemail.mail.aliyun.com ([115.124.30.131]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mQKAm-007sDd-66 for linux-arm-kernel@lists.infradead.org; Wed, 15 Sep 2021 01:57:17 +0000 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R931e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04400; MF=ashimida@linux.alibaba.com; NM=1; PH=DS; RN=6; SR=0; TI=SMTPD_---0UoQf.bx_1631671032; Received: from ashimida.local(mailfrom:ashimida@linux.alibaba.com fp:SMTPD_---0UoQf.bx_1631671032) by smtp.aliyun-inc.com(127.0.0.1); Wed, 15 Sep 2021 09:57:13 +0800 Subject: Re: [PATCH] [RFC]arm64:Mark __stack_chk_guard as __ro_after_init To: Mark Rutland Cc: catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Laura Abbott References: <1631612642-102881-1-git-send-email-ashimida@linux.alibaba.com> <20210914101709.GA29127@C02TD0UTHF1T.local> From: ashimida Message-ID: Date: Wed, 15 Sep 2021 09:57:14 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <20210914101709.GA29127@C02TD0UTHF1T.local> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210914_185716_449014_2417F7E9 X-CRM114-Status: GOOD ( 22.30 ) 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi King, Rutland: Thanks for the reply and let me understand the reason here. Then may I first submit a patch to modify the attributes of __stack_chk_guard of the arm/aarch64 platform? On 9/14/21 6:17 PM, Mark Rutland wrote: > On Tue, Sep 14, 2021 at 05:44:02PM +0800, Dan Li wrote: >> __stack_chk_guard is setup once while init stage and never changed >> after that. >> >> Although the modification of this variable at runtime will usually >> cause the kernel to crash (so dose the attacker), it should be marked >> as _ro_after_init, and it should not affect performance if it is >> placed in the ro_after_init section. >> >> This should also be the case on the ARM platform, or am I missing >> something? >> >> Signed-off-by: Dan Li > > FWIW, this makes sense to me: > > Acked-by: Mark Rutland > > Looking at the history, this was added to arm64 in commit: > > c0c264ae5112d1cd ("arm64: Add CONFIG_CC_STACKPROTECTOR") > > ... whereas __ro_after_init was introduced around 2 years later in > commit: > > c74ba8b3480da6dd ("arch: Introduce post-init read-only memory") > > ... so we weren't deliberately avoiding __ro_after_init, and there are > probably a significant number of other variables we could apply it to. > > Mark. > >> --- >> arch/arm64/kernel/process.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c >> index c8989b9..c858b85 100644 >> --- a/arch/arm64/kernel/process.c >> +++ b/arch/arm64/kernel/process.c >> @@ -60,7 +60,7 @@ >> >> #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK) >> #include >> -unsigned long __stack_chk_guard __read_mostly; >> +unsigned long __stack_chk_guard __ro_after_init; >> EXPORT_SYMBOL(__stack_chk_guard); >> #endif >> >> -- >> 2.7.4 >> _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel