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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_NEOMUTT 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 DD115C43441 for ; Sun, 11 Nov 2018 17:32:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8FB33214DB for ; Sun, 11 Nov 2018 17:32:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8FB33214DB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729277AbeKLDVY (ORCPT ); Sun, 11 Nov 2018 22:21:24 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:51260 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729222AbeKLDVY (ORCPT ); Sun, 11 Nov 2018 22:21:24 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 16D4D80D; Sun, 11 Nov 2018 09:32:16 -0800 (PST) Received: from salmiak (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 140C53F5BD; Sun, 11 Nov 2018 09:32:14 -0800 (PST) Date: Sun, 11 Nov 2018 17:32:12 +0000 From: Mark Rutland To: Zhizhou Zhang Cc: rostedt@goodmis.org, mingo@redhat.com, linux-kernel@vger.kernel.org, zhizhouzh@gmail.com Subject: Re: [PATCH] ftrace: remove KASAN poison in ftrace_ops_test() Message-ID: <20181111173211.q2gzf7h4htxbezch@salmiak> References: <1541949017-3001-1-git-send-email-zhizhouzhang@asrmicro.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1541949017-3001-1-git-send-email-zhizhouzhang@asrmicro.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Nov 11, 2018 at 11:10:17PM +0800, Zhizhou Zhang wrote: > ftrace_ops_test() passed local varible parameter to hash_contains_ip(), > which could result KASAN stack-out-of-bounds warning. > > Signed-off-by: Zhizhou Zhang > --- > kernel/trace/ftrace.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index f536f60..6e11f90 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -1522,6 +1522,8 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs) > rcu_assign_pointer(hash.filter_hash, ops->func_hash->filter_hash); > rcu_assign_pointer(hash.notrace_hash, ops->func_hash->notrace_hash); > > + kasan_unpoison_task_stack(current); This is extremely heavy-handed, and will mask legitimate stack-out-of-bounds errors. Passing a stack-local variable by reference *should not* result in KASAN warnings unless KASAN itself is broken. Can you please give an example report when this occurs? Which compiler are you using? Thanks, Mark. > + > if (hash_contains_ip(ip, &hash)) > ret = 1; > else > -- > 2.7.4 >