[PATCH v1 10/11] perf intel-pt: Smatch: Fix potential NULL pointer dereference

Leo Yan
2019-07-02T10:38:28Z

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@linaro.org>
---
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