[PATCH v1 10/11] perf intel-pt: 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-pt.c:3200
  intel_pt_process_auxtrace_info() error: we previously assumed
  'session->itrace_synth_opts' could be null (see line 3196)

  tools/perf/util/intel-pt.c:3206
  intel_pt_process_auxtrace_info() warn: variable dereferenced before
  check 'session->itrace_synth_opts' (see line 3200)

tools/perf/util/intel-pt.c
3196         if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
3197                 pt->synth_opts = *session->itrace_synth_opts;
3198         } else {
3199                 itrace_synth_opts__set_default(&pt->synth_opts,
3200                                 session->itrace_synth_opts->default_no_sample);
                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^
3201                 if (!session->itrace_synth_opts->default_no_sample &&
3202                     !session->itrace_synth_opts->inject) {
3203                         pt->synth_opts.branches = false;
3204                         pt->synth_opts.callchain = true;
3205                 }
3206                 if (session->itrace_synth_opts)
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^
3207                         pt->synth_opts.thread_stack =
3208                                 session->itrace_synth_opts->thread_stack;
3209         }

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-pt.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 550db6e77968..88b567bdf1f9 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -3195,7 +3195,7 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
 
 	if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
 		pt->synth_opts = *session->itrace_synth_opts;
-	} else {
+	} else if (session->itrace_synth_opts) {
 		itrace_synth_opts__set_default(&pt->synth_opts,
 				session->itrace_synth_opts->default_no_sample);
 		if (!session->itrace_synth_opts->default_no_sample &&
@@ -3203,8 +3203,7 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
 			pt->synth_opts.branches = false;
 			pt->synth_opts.callchain = true;
 		}
-		if (session->itrace_synth_opts)
-			pt->synth_opts.thread_stack =
+		pt->synth_opts.thread_stack =
 				session->itrace_synth_opts->thread_stack;
 	}
 
-- 
2.17.1