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From:   Namhyung Kim <namhyung@kernel.org>
Date:   Sat, 13 Jun 2020 00:19:10 +0900
Message-ID: <CAM9d7cjK=TN8-0kaWtMo2vPq_AzsmFwM9z=f_ni7qD2r9-8FDQ@mail.gmail.com>
Subject: Re: [PATCH] perf report TUI: Fix segmentation fault in perf_evsel__hists_browse()
To:     Wei Li <liwei391@huawei.com>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Jin Yao <yao.jin@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>, guohanjun@huawei.com
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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
>