Re: [PATCH v2 1/3] perf hists browser: Fix segfault if use symbol filter in cmdline

[Namhyung Kim <namhyung@kernel.org>]

On Thu, Dec 03, 2015 at 03:08:13AM +0000, Wang Nan wrote:
> If feed perf a symbol filter in cmdline and the result is empty,
> pressing 'Enter' in the hist browser causes crash:
> 
>  # ./perf report perf.data   <-- Common mistake for beginners
> 
> Then press 'Enter':
> 
>  perf: Segmentation fault
>  -------- backtrace --------
>  /home/wangnan/perf[0x53e578]
>  /lib64/libc.so.6(+0x3545f)[0x7f76bafe045f]
>  /home/wangnan/perf[0x539dd4]
>  /home/wangnan/perf(perf_evlist__tui_browse_hists+0x96)[0x53d216]
>  /home/wangnan/perf(cmd_report+0x1b9f)[0x442c7f]
>  /home/wangnan/perf[0x47efa2]
>  /home/wangnan/perf(main+0x5f5)[0x432fa5]
>  /lib64/libc.so.6(__libc_start_main+0xf4)[0x7f76bafccbd4]
>  /home/wangnan/perf[0x4330d4]
> 
> This is because 'perf.data' is interperted as a symbol filter, and the
> result is empty, so selection is empty. However,
> hist_browser__toggle_fold() forgets to check it.
> 
> This patch simply return false when selection is NULL.
> 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> Acked-by: Namhyung Kim <namhyung@kernel.org>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
>  tools/perf/ui/browsers/hists.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
> index dcdcbaf..601a585 100644
> --- a/tools/perf/ui/browsers/hists.c
> +++ b/tools/perf/ui/browsers/hists.c
> @@ -340,6 +340,9 @@ static bool hist_browser__toggle_fold(struct hist_browser *browser)
>  	struct callchain_list *cl = container_of(ms, struct callchain_list, ms);
>  	bool has_children;
>  
> +	if (!ms)
> +		return false;
> +

I'm ok with this change itself.  But as other code checks the
browser->he_selection, it'd be better to check 'he' here for
consistency.

Thanks,
Namhyung


>  	if (ms == &he->ms)
>  		has_children = hist_entry__toggle_fold(he);
>  	else
> -- 
> 1.8.3.4
>