linux-kernel - [PATCH v2 3/4] perf intel-pt: Smatch: Fix potential NULL pointer dereference

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Message-Id: <20190708143937.7722-4-leo.yan@linaro.org>
Date:   Mon,  8 Jul 2019 22:39:36 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <ak@...ux.intel.com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v2 3/4] perf intel-pt: Smatch: Fix potential NULL pointer dereference

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@...aro.org>
---
 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 |
-- 
2.17.1