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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 ACEA8C5B578 for ; Wed, 3 Jul 2019 05:20:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 83B5C21871 for ; Wed, 3 Jul 2019 05:20:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726400AbfGCFUd (ORCPT ); Wed, 3 Jul 2019 01:20:33 -0400 Received: from mga14.intel.com ([192.55.52.115]:7183 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725828AbfGCFUd (ORCPT ); Wed, 3 Jul 2019 01:20:33 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 02 Jul 2019 22:20:32 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,445,1557212400"; d="scan'208";a="164232322" Received: from ahunter-desktop.fi.intel.com (HELO [10.237.72.122]) ([10.237.72.122]) by fmsmga008.fm.intel.com with ESMTP; 02 Jul 2019 22:20:27 -0700 Subject: Re: [PATCH v1 10/11] perf intel-pt: Smatch: Fix potential NULL pointer dereference To: Leo Yan Cc: Arnaldo Carvalho de Melo , Peter Zijlstra , Ingo Molnar , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Mathieu Poirier , Suzuki K Poulose , Andi Kleen , "David S. Miller" , Davidlohr Bueso , Rasmus Villemoes , Jin Yao , Song Liu , Alexios Zavras , Thomas Gleixner , Changbin Du , Eric Saint-Etienne , Konstantin Khlebnikov , Thomas Richter , Alexey Budankov , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20190702103420.27540-1-leo.yan@linaro.org> <20190702103420.27540-11-leo.yan@linaro.org> <20190703013553.GB6852@leoy-ThinkPad-X240s> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: Date: Wed, 3 Jul 2019 08:19:19 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190703013553.GB6852@leoy-ThinkPad-X240s> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/07/19 4:35 AM, Leo Yan wrote: > Hi Adrian, > > On Tue, Jul 02, 2019 at 02:07:40PM +0300, Adrian Hunter wrote: >> On 2/07/19 1:34 PM, Leo Yan wrote: >>> Based on the following report from Smatch, fix the potential >>> NULL pointer dereference check. >> >> It never is NULL. Remove the NULL test if you want: >> >> - if (session->itrace_synth_opts && session->itrace_synth_opts->set) { >> + if (session->itrace_synth_opts->set) { >> >> But blindly making changes like below is questionable. > > Thanks for suggestions. > > I checked report and script commands, as you said, both command will > always set session->itrace_synth_opts. For these two commands, we can > safely remove the NULL test. > > Because perf tool contains many sub commands, so I don't have much > confidence it's very safe to remove the NULL test for all cases; e.g. > there have cases which will process aux trace buffer but without > itrace options; for this case, session->itrace_synth_opts might be NULL. > > For either way (remove NULL test or keep NULL test), I don't want to > introduce regression and extra efforts by my patch. So want to double > confirm with you for this :) Yes, intel_pt_process_auxtrace_info() only gets called if a tool sets up the tools->auxtrace_info() callback. The tools that do that also set session->itrace_synth_opts.