From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753659AbbIKQZ2 (ORCPT ); Fri, 11 Sep 2015 12:25:28 -0400 Received: from mail-pa0-f41.google.com ([209.85.220.41]:35167 "EHLO mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750819AbbIKQZ1 (ORCPT ); Fri, 11 Sep 2015 12:25:27 -0400 Date: Sat, 12 Sep 2015 01:22:07 +0900 From: Namhyung Kim To: Wang Nan Cc: acme@kernel.org, lizefan@huawei.com, linux-kernel@vger.kernel.org, pi3orama@163.com Subject: Re: [PATCH] perf tools: Fix segfault in 'perf top' Message-ID: <20150911162207.GD3447@danjae.kornet> References: <1441947551-48992-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1441947551-48992-1-git-send-email-wangnan0@huawei.com> User-Agent: Mutt/1.5.23+102 (2ca89bed6448) (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 11, 2015 at 04:59:11AM +0000, Wang Nan wrote: > 'perf top' segfaults with following operation: > > # perf top -e page-faults -p 15173 # 15173 never generate page-fault > > Then on the resulting empty interface, press right key: > > # ./perf top -e page-faults -p 11400 > perf: Segmentation fault > -------- backtrace -------- > ./perf[0x535428] > /lib64/libc.so.6(+0x3545f)[0x7f0dd360745f] > ./perf[0x531d46] > ./perf(perf_evlist__tui_browse_hists+0x96)[0x5340d6] > ./perf[0x44ba2f] > /lib64/libpthread.so.0(+0x81d0)[0x7f0dd49dc1d0] > /lib64/libc.so.6(clone+0x6c)[0x7f0dd36b90dc] > > The bug reside in perf_evsel__hists_browse() that, in the above circumstance > browser->selection can be NULL, but code after skip_annotation doesn't consider > it. > > This patch fix it by checing browser->selection before fetching > browser->selection->map and browser->selection->sym. I'm ok with this change, just a nitpick below.. > > Signed-off-by: Wang Nan > Cc: Arnaldo Carvalho de Melo > Cc: Namhyung Kim > --- > tools/perf/ui/browsers/hists.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c > index e4fd40f..b00fa92 100644 > --- a/tools/perf/ui/browsers/hists.c > +++ b/tools/perf/ui/browsers/hists.c > @@ -2017,7 +2017,8 @@ skip_annotation: > &options[nr_options], dso); > nr_options += add_map_opt(browser, &actions[nr_options], > &options[nr_options], > - browser->selection->map); > + browser->selection ? > + browser->selection->map : NULL); > nr_options += add_socket_opt(browser, &actions[nr_options], > &options[nr_options], > socket); > @@ -2030,7 +2031,10 @@ skip_annotation: > nr_options += add_script_opt(browser, > &actions[nr_options], > &options[nr_options], > - NULL, browser->selection->sym); > + NULL, > + browser->selection ? > + browser->selection->sym : > + NULL); Is this really needed? IIUC browser->selection is not NULL if browser->he_selection is not NULL. Did you see a case it's NULL? Also passing a NULL thread and a NULL sym is meaningless here since it's a duplication.. Thanks, Namhyung > } > nr_options += add_script_opt(browser, &actions[nr_options], > &options[nr_options], NULL, NULL); > -- > 1.8.3.4 >