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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B395C433EF for ; Mon, 24 Jan 2022 15:30:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234124AbiAXPaV (ORCPT ); Mon, 24 Jan 2022 10:30:21 -0500 Received: from foss.arm.com ([217.140.110.172]:37896 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240713AbiAXPaV (ORCPT ); Mon, 24 Jan 2022 10:30:21 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 949CD6D; Mon, 24 Jan 2022 07:30:20 -0800 (PST) Received: from [10.57.39.131] (unknown [10.57.39.131]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 915183F7D8; Mon, 24 Jan 2022 07:30:18 -0800 (PST) Subject: Re: [PATCH] perf session: check for null pointer before derefernce To: Ameer Hamza , German Gomez Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, rickyman7@gmail.com, alexey.v.bayduraev@linux.intel.com, adrian.hunter@intel.com, leo.yan@linaro.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org References: <20220124150001.93145-1-amhamza.mgc@gmail.com> From: James Clark Message-ID: <7c068167-e8bb-74f3-97d9-dd0c5858ee19@arm.com> Date: Mon, 24 Jan 2022 15:30:17 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20220124150001.93145-1-amhamza.mgc@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On 24/01/2022 15:00, Ameer Hamza wrote: > Move null pointer check before dereferncing the variable > > Addresses-Coverity: 1497622 ("Derereference before null check") > > Signed-off-by: Ameer Hamza > --- > tools/perf/util/session.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c > index f19348dddd55..e1014ab62c10 100644 > --- a/tools/perf/util/session.c > +++ b/tools/perf/util/session.c > @@ -1503,11 +1503,11 @@ static int machines__deliver_event(struct machines *machines, > ++evlist->stats.nr_unknown_id; > return 0; > } > - dump_sample(evsel, event, sample, perf_env__arch(machine->env)); > if (machine == NULL) { > ++evlist->stats.nr_unprocessable_samples; > return 0; > } > + dump_sample(evsel, event, sample, perf_env__arch(machine->env)); > return evlist__deliver_sample(evlist, tool, event, sample, evsel, machine); > case PERF_RECORD_MMAP: > return tool->mmap(tool, event, sample, machine); > Hi Ameer, This mistake was made recently, but I don't think your change is the desired behavior. It should be possible to dump stuff if machine is null. null or an empty string should be passed to dump_sample(). It looks like some of the printfs still attempt to show something in this case, although I didn't check them all. James