Re: [PATCH] perf report TUI: Fix segmentation fault in perf_evsel__hists_browse()

[Jiri Olsa <jolsa@redhat.com>]

On Fri, Jun 12, 2020 at 05:43:22PM +0800, Wei Li 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: Jiri Olsa <jolsa@redhat.com>

thanks,
jirka

> ---
>  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
>