Messages in this thread | | | Date | Tue, 2 Jul 2019 11:03:06 -0600 | From | Mathieu Poirier <> | Subject | Re: [PATCH v1 11/11] perf cs-etm: Smatch: Fix potential NULL pointer dereference |
| |
Hi Leo,
On Tue, Jul 02, 2019 at 06:34:20PM +0800, Leo Yan 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 } > > To dismiss the potential NULL pointer dereference, this patch validates > the pointer 'session->itrace_synth_opts' before access its elements. > > 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 0c7776b51045..b79df56eb9df 100644 > --- a/tools/perf/util/cs-etm.c > +++ b/tools/perf/util/cs-etm.c > @@ -2540,7 +2540,7 @@ int cs_etm__process_auxtrace_info(union perf_event *event, > > if (session->itrace_synth_opts && session->itrace_synth_opts->set) { > etm->synth_opts = *session->itrace_synth_opts; > - } else { > + } else if (session->itrace_synth_opts) {
This will work but we end up checking session->itrace_synth_opts twice. I suggest to check it once and then process with the if/else if valid:
if (session->itrace_synth_opts) { if (session->itrace_synth_opts->set) { ... } else { ... } }
Thanks, Mathieu
> itrace_synth_opts__set_default(&etm->synth_opts, > session->itrace_synth_opts->default_no_sample); > etm->synth_opts.callchain = false; > -- > 2.17.1 >
| |