[PATCH 25/25] perf intel-pt: Fix potential NULL pointer dereference found by the smatch tool

Arnaldo Carvalho de Melo
2019-07-09T18:33:31Z

From: Leo Yan <leo.yan@linaro.org>

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 }

'session->itrace_synth_opts' is impossible to be a NULL pointer in
intel_pt_process_auxtrace_info(), thus this patch removes the NULL test
for 'session->itrace_synth_opts'.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20190708143937.7722-4-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/intel-pt.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index c76a96f777fb..df061599fef4 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -3210,7 +3210,7 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
goto err_delete_thread;
}

- if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
+ if (session->itrace_synth_opts->set) {
pt->synth_opts = *session->itrace_synth_opts;
} else {
itrace_synth_opts__set_default(&pt->synth_opts,
@@ -3220,8 +3220,7 @@ 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;
}

@@ -3241,11 +3240,9 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
pt->cbr2khz = tsc_freq / pt->max_non_turbo_ratio / 1000;
}

- if (session->itrace_synth_opts) {
- err = intel_pt_setup_time_ranges(pt, session->itrace_synth_opts);
- if (err)
- goto err_delete_thread;
- }
+ err = intel_pt_setup_time_ranges(pt, session->itrace_synth_opts);
+ if (err)
+ goto err_delete_thread;

if (pt->synth_opts.calls)
pt->branches_filter |= PERF_IP_FLAG_CALL | PERF_IP_FLAG_ASYNC |
--
2.21.0