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

Leo Yan
2019-07-02T10:38:06Z

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@linaro.org>
---
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