Re: [PATCH v2] perf: fix double free at function perf_hpp__reset_output_field

From: Du, Changbin
Date: Tue Apr 11 2017 - 06:16:29 EST


> > >
> > yes, this is an option. But for safety, I sugguest do not rely on list_del_init.
> > No rule rather than create one.
> >
> > But anyway, both are ok for me. What's your options?
>
> hum, also I dont think we need to touch that bit at all
> if we are going to remove it right away.. how about the
> change below?
>
> jirka
>
>
> ---
> diff --git a/tools/perf/ui/hist.c b/tools/perf/ui/hist.c
> index 5d632dca672a..0ee7db43dd7d 100644
> --- a/tools/perf/ui/hist.c
> +++ b/tools/perf/ui/hist.c
> @@ -613,15 +613,15 @@ void perf_hpp__reset_output_field(struct perf_hpp_list *list)
>
> /* reset output fields */
> perf_hpp_list__for_each_format_safe(list, fmt, tmp) {
> - list_del_init(&fmt->list);
> - list_del_init(&fmt->sort_list);
> + list_del(&fmt->list);
> + /* Remove the fmt from next loop processing. */
> + list_del(&fmt->sort_list);
> fmt_free(fmt);
What if the fmt is not linked to sort_list? I see it is possible (please
checking perf_hpp__setup_output_field()). I am not sure if we really has
sunch case currently, just concern :)

> }
>
> /* reset sort keys */
> perf_hpp_list__for_each_sort_list_safe(list, fmt, tmp) {
> - list_del_init(&fmt->list);
> - list_del_init(&fmt->sort_list);
> + list_del(&fmt->sort_list);
> fmt_free(fmt);
> }
> }

--
Thanks,
Changbin Du

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