[PATCH v1 09/11] perf intel-bts: Smatch: Fix potential NULL pointer dereference

[Leo Yan]

Based on the following report from Smatch, fix the potential
NULL pointer dereference check.

  tools/perf/util/intel-bts.c:898
  intel_bts_process_auxtrace_info() error: we previously assumed
  'session->itrace_synth_opts' could be null (see line 894)

  tools/perf/util/intel-bts.c:899
  intel_bts_process_auxtrace_info() warn: variable dereferenced before
  check 'session->itrace_synth_opts' (see line 898)

tools/perf/util/intel-bts.c
894         if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
895                 bts->synth_opts = *session->itrace_synth_opts;
896         } else {
897                 itrace_synth_opts__set_default(&bts->synth_opts,
898                                 session->itrace_synth_opts->default_no_sample);
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^
899                 if (session->itrace_synth_opts)
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^
900                         bts->synth_opts.thread_stack =
901                                 session->itrace_synth_opts->thread_stack;
902         }

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@xxxxxxxxxx>
---
 tools/perf/util/intel-bts.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index e32dbffebb2f..332e647fecaa 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -893,11 +893,10 @@ int intel_bts_process_auxtrace_info(union perf_event *event,
 
 	if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
 		bts->synth_opts = *session->itrace_synth_opts;
-	} else {
+	} else if (session->itrace_synth_opts) {
 		itrace_synth_opts__set_default(&bts->synth_opts,
 				session->itrace_synth_opts->default_no_sample);
-		if (session->itrace_synth_opts)
-			bts->synth_opts.thread_stack =
+		bts->synth_opts.thread_stack =
 				session->itrace_synth_opts->thread_stack;
 	}
 
-- 
2.17.1