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Subject: Re: [PATCH] perf report TUI: Fix segmentation fault in
 perf_evsel__hists_browse()
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>
CC:     Namhyung Kim <namhyung@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Jin Yao <yao.jin@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>, <guohanjun@huawei.com>
References: <20200612094322.39565-1-liwei391@huawei.com>
 <CAM9d7cjK=TN8-0kaWtMo2vPq_AzsmFwM9z=f_ni7qD2r9-8FDQ@mail.gmail.com>
From:   "liwei (GF)" <liwei391@huawei.com>
Message-ID: <48be67be-9b87-87a1-125a-bb7d0d027a57@huawei.com>
Date:   Fri, 3 Jul 2020 09:03:53 +0800
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On 2020/6/12 23:19, Namhyung Kim wrote:
> Hello,
> 
> On Fri, Jun 12, 2020 at 6:58 PM Wei Li <liwei391@huawei.com> wrote:
>>
>> The segmentation fault can be reproduced as following steps:
>> 1) Executing perf report in tui.
>> 2) Typing '/xxxxx' to filter the symbol to get nothing matched.
>> 3) Pressing enter with no entry selected.
>> Then it will report a segmentation fault.
>>
>> It is caused by the lack of check of browser->he_selection when
>> accessing it's member res_samples in perf_evsel__hists_browse().
>>
>> These processes are meaningful for specified samples, so we can
>> skip these when nothing is selected.
>>
>> Fixes: 4968ac8fb7c3 ("perf report: Implement browsing of individual samples")
>> Signed-off-by: Wei Li <liwei391@huawei.com>
> 
> Acked-by: Namhyung Kim <namhyung@kernel.org>
> 
> Thanks
> Namhyung
> 
> 
>> ---
>>  tools/perf/ui/browsers/hists.c | 17 +++++++++++------
>>  1 file changed, 11 insertions(+), 6 deletions(-)
>>
>> diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
>> index 487e54ef56a9..2101b6b770d8 100644
>> --- a/tools/perf/ui/browsers/hists.c
>> +++ b/tools/perf/ui/browsers/hists.c
>> @@ -2288,6 +2288,11 @@ static struct thread *hist_browser__selected_thread(struct hist_browser *browser
>>         return browser->he_selection->thread;
>>  }
>>
>> +static struct res_sample *hist_browser__selected_res_sample(struct hist_browser *browser)
>> +{
>> +       return browser->he_selection ? browser->he_selection->res_samples : NULL;
>> +}
>> +
>>  /* Check whether the browser is for 'top' or 'report' */
>>  static inline bool is_report_browser(void *timer)
>>  {
>> @@ -3357,16 +3362,16 @@ static int perf_evsel__hists_browse(struct evsel *evsel, int nr_events,
>>                                              &options[nr_options], NULL, NULL, evsel);
>>                 nr_options += add_res_sample_opt(browser, &actions[nr_options],
>>                                                  &options[nr_options],
>> -                                hist_browser__selected_entry(browser)->res_samples,
>> -                                evsel, A_NORMAL);
>> +                                                hist_browser__selected_res_sample(browser),
>> +                                                evsel, A_NORMAL);
>>                 nr_options += add_res_sample_opt(browser, &actions[nr_options],
>>                                                  &options[nr_options],
>> -                                hist_browser__selected_entry(browser)->res_samples,
>> -                                evsel, A_ASM);
>> +                                                hist_browser__selected_res_sample(browser),
>> +                                                evsel, A_ASM);
>>                 nr_options += add_res_sample_opt(browser, &actions[nr_options],
>>                                                  &options[nr_options],
>> -                                hist_browser__selected_entry(browser)->res_samples,
>> -                                evsel, A_SOURCE);
>> +                                                hist_browser__selected_res_sample(browser),
>> +                                                evsel, A_SOURCE);
>>                 nr_options += add_switch_opt(browser, &actions[nr_options],
>>                                              &options[nr_options]);
>>  skip_scripting:
>> --
>> 2.17.1
>>