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=-14.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 864F2C43331 for ; Wed, 25 Mar 2020 21:36:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 55D9E2070A for ; Wed, 25 Mar 2020 21:36:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Jvkg5nCB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727592AbgCYVf7 (ORCPT ); Wed, 25 Mar 2020 17:35:59 -0400 Received: from mail-yb1-f194.google.com ([209.85.219.194]:43312 "EHLO mail-yb1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726664AbgCYVf7 (ORCPT ); Wed, 25 Mar 2020 17:35:59 -0400 Received: by mail-yb1-f194.google.com with SMTP id o70so2048382ybg.10 for ; Wed, 25 Mar 2020 14:35:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=kM5tF24jxTWZD1wcuGGjp7ru29LzT/mQ5FW1gUutUcg=; b=Jvkg5nCBH7SaM73Ih/ExS64TqRps5KxwLAt5AkSNFbQ2NaFsbupv6ZGsL4OFXjHFQp zyOwTFAKLAVXhybap93Tqb5KTYsVXJ4B6jE76fXf1VLfLxv1MAYQ0N7X8NV1D6BaFVyO N/dUkhL9rIabj4iJk3Ltc3fnpLiu6NX6Yi2DfseSoW44F8xbzcJsI5qtGdAJEYvmOEGh Z/+G076l+5TTBNscJQ4WHEhkPNwRpfPgQerHBxDsMveMJ4gW79oWU2ea38I59pSPklOP glGfRnd5zX2Ix2xa9MMBoNFZdWLUscsAaCXtSx4Cvno7pVrGk8o85IUGonRtbxsPVJMj 4YMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=kM5tF24jxTWZD1wcuGGjp7ru29LzT/mQ5FW1gUutUcg=; b=Q6itPr5/75pQPceZr0WSDMah4xH1ak6OBl2RTrwXwslVxHOH0KiiNf32uEnyCwg7lV q5rpWzt20708vesyyfjv1+W4siDvazpYyaAz4SBujX5BTcCxjf5I1KBuAZITjET4lQPZ IHKpTic8gUbArVVL8bnt3bS9BQ1+jP8NWtS9Mrc991G3YyTxswha+p7d6BsAVuB12Z81 IjommDkJKCWTi2tNOZTWr4Bov523RaI9eHHVYl+8ZVrX8UzNBQ57efPN3kYtQeVER5Q5 UxC3uhxGLEMVBfsjWgcjgLMWLufaqfr/nyeA+T1ilGWXWJU1RCju8NMOs3VbqpI20bdi 390A== X-Gm-Message-State: ANhLgQ2yyxlmdJImPSM35wdSXjqg1biVMgKB6crHZ7p54ixMJM/qlxUj IOZ76yg1La0HNnKo1r7qH8qbIyH2BTZZa3NFBJau9Q== X-Google-Smtp-Source: ADFU+vuqVso8c9jgap1aIZDGTidCgKYfx270CJryNHCPFX7CUmVG0fGeNNOqJwIZBgKz8DT8Qjc3y2UFprHn6+s2FiE= X-Received: by 2002:a25:aaa4:: with SMTP id t33mr9126430ybi.324.1585172156837; Wed, 25 Mar 2020 14:35:56 -0700 (PDT) MIME-Version: 1.0 References: <20200325164022.41385-1-irogers@google.com> <20200325192539.GH14102@kernel.org> In-Reply-To: <20200325192539.GH14102@kernel.org> From: Ian Rogers Date: Wed, 25 Mar 2020 14:35:45 -0700 Message-ID: Subject: Re: [PATCH] perf parse-events: add defensive null check To: Arnaldo Carvalho de Melo Cc: Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , John Garry , Jin Yao , Andi Kleen , Kan Liang , LKML , clang-built-linux , Stephane Eranian Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 25, 2020 at 12:25 PM Arnaldo Carvalho de Melo wrote: > > Em Wed, Mar 25, 2020 at 09:40:22AM -0700, Ian Rogers escreveu: > > Terms may have a null config in which case a strcmp will segv. This can > > be reproduced with: > > perf stat -e '*/event=?,nr/' sleep 1 > > Add a null check to avoid this. This was caught by LLVM's libfuzzer. > > Adding the NULL check doesn't hurt, I guess, but I coudln't repro it: > > [root@seventh ~]# perf stat -e '*/event=?,nr/' sleep 1 > WARNING: multiple event parsing errors > event syntax error: '*/event=?,nr/' > \___ 'nr' is not usable in 'perf stat' > > Initial error: > event syntax error: '*/event=?,nr/' > \___ Cannot find PMU `*'. Missing kernel support? > Run 'perf list' for a list of valid events > > Usage: perf stat [] [] > > -e, --event event selector. use 'perf list' to list available events > [root@seventh ~]# > > Does this take place only when libfuzzer is being used? Good catch! I was driving the repro through the fuzzer and getting the stack trace below and had assumed this would repro on the command line. I'm now wondering why it won't reproduce :-) I suspect this issue can come up in other scenarios so as you say the null check won't hurt, but the commit message is incorrect. #0 __interceptor_strcmp () at llvm/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc:448 #1 0x0000555557345eb2 in pmu_resolve_param_term (term=0x607000081190, head_terms=0x602000007cb0, value=0x7ffff4cc0320) at tools/perf/util/pmu.c:994 #2 0x00005555573389a4 in pmu_config_term (formats=0x6080000012c8, attr=0x7ffff4dd4e20, term=0x607000081190, head_terms=0x602000007cb0, zero=false, err=0x7ffff4c90020) at tools/perf/util/pmu.c:1117 #3 0x0000555557337b4e in perf_pmu__config_terms (formats=0x6080000012c8, attr=0x7ffff4dd4e20, head_terms=0x602000007cb0, zero=false, err=0x7ffff4c90020) at tools/perf/util/pmu.c:1154 #4 0x0000555557338f7e in perf_pmu__config (pmu=0x6080000012a0, attr=0x7ffff4dd4e20, head_terms=0x602000007cb0, err=0x7ffff4c90020) at tools/perf/util/pmu.c:1174 #5 0x0000555557314027 in parse_events_add_pmu (parse_state=0x7ffff4c900a0, list=0x602000007e10, name=0x602000001910 "uncore_cha_1", head_config=0x602000007cb0, auto_merge_stats=true, use_alias=false) at tools/perf/util/parse-events.c:1485 #6 0x0000555556d257f9 in parse_events_parse (_parse_state=0x7ffff4c900a0, scanner=0x611000000cc0) at tools/perf/util/parse-events.y:318 #7 0x000055555731c573 in parse_events__scanner (str=0x7ffff4d85c40 "*/event=?,nr/", parse_state=0x7ffff4c900a0, start_token=258) at tools/perf/util/parse-events.c:2026 #8 0x000055555731cbc3 in parse_events (evlist=0x61e000000080, str=0x7ffff4d85c40 "*/event=?,nr/", err=0x7ffff4c90020) at tools/perf/util/parse-events.c:2066 Thanks, Ian > - Arnaldo > > > Signed-off-by: Ian Rogers > > --- > > tools/perf/util/pmu.c | 11 +++++------ > > 1 file changed, 5 insertions(+), 6 deletions(-) > > > > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c > > index 616fbda7c3fc..ef6a63f3d386 100644 > > --- a/tools/perf/util/pmu.c > > +++ b/tools/perf/util/pmu.c > > @@ -984,12 +984,11 @@ static int pmu_resolve_param_term(struct parse_events_term *term, > > struct parse_events_term *t; > > > > list_for_each_entry(t, head_terms, list) { > > - if (t->type_val == PARSE_EVENTS__TERM_TYPE_NUM) { > > - if (!strcmp(t->config, term->config)) { > > - t->used = true; > > - *value = t->val.num; > > - return 0; > > - } > > + if (t->type_val == PARSE_EVENTS__TERM_TYPE_NUM && > > + t->config && !strcmp(t->config, term->config)) { > > + t->used = true; > > + *value = t->val.num; > > + return 0; > > } > > } > > > > -- > > 2.25.1.696.g5e7596f4ac-goog > > > > -- > > - Arnaldo