linux-kernel - Re: [PATCH v2 4/4] perf cs-etm: Smatch: Fix potential NULL pointer dereference

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Message-ID: <CANLsYkwHMfVf-FUQ+wBkDfq9GnCihimFAhd+ybCsxMAt8d3HcA@mail.gmail.com>
Date:   Mon, 8 Jul 2019 11:38:48 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Leo Yan <leo.yan@...aro.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 4/4] perf cs-etm: Smatch: Fix potential NULL pointer dereference

On Mon, 8 Jul 2019 at 08:40, Leo Yan <leo.yan@...aro.org> wrote:
>
> Based on the following report from Smatch, fix the potential
> NULL pointer dereference check.
>
>   tools/perf/util/cs-etm.c:2545
>   cs_etm__process_auxtrace_info() error: we previously assumed
>   'session->itrace_synth_opts' could be null (see line 2541)
>
> tools/perf/util/cs-etm.c
> 2541         if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
> 2542                 etm->synth_opts = *session->itrace_synth_opts;
> 2543         } else {
> 2544                 itrace_synth_opts__set_default(&etm->synth_opts,
> 2545                                 session->itrace_synth_opts->default_no_sample);
>                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
> 2546                 etm->synth_opts.callchain = false;
> 2547         }
>
> 'session->itrace_synth_opts' is impossible to be a NULL pointer in
> cs_etm__process_auxtrace_info(), thus this patch removes the NULL
> test for 'session->itrace_synth_opts'.
>
> Signed-off-by: Leo Yan <leo.yan@...aro.org>
> ---
>  tools/perf/util/cs-etm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index ad43a6e31827..ab578a06a790 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -2537,7 +2537,7 @@ int cs_etm__process_auxtrace_info(union perf_event *event,
>                 return 0;
>         }
>
> -       if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
> +       if (session->itrace_synth_opts->set) {
>                 etm->synth_opts = *session->itrace_synth_opts;
>         } else {
>                 itrace_synth_opts__set_default(&etm->synth_opts,

This is in accordance with what was previously discussed.

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>

> --
> 2.17.1
>