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

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Andi Kleen <ak@linux.intel.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Leo Yan <leo.yan@linaro.org>, Namhyung Kim <namhyung@kernel.org>,
	Jiri Olsa <jolsa@redhat.com>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 4/4] perf cs-etm: Smatch: Fix potential NULL pointer dereference
Date: Mon, 8 Jul 2019 18:57:38 -0300	[thread overview]
Message-ID: <20190708215738.GC7455@kernel.org> (raw)
In-Reply-To: <CANLsYkwHMfVf-FUQ+wBkDfq9GnCihimFAhd+ybCsxMAt8d3HcA@mail.gmail.com>

Em Mon, Jul 08, 2019 at 11:38:48AM -0600, Mathieu Poirier escreveu:
> On Mon, 8 Jul 2019 at 08:40, Leo Yan <leo.yan@linaro.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@linaro.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@linaro.org>

Thanks, applied.

- Arnaldo

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