linux-kernel - [tip:perf/urgent] perf intel-bts: Fix potential NULL pointer dereference found by the smatch tool

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Message-ID: <tip-1d481458816d9424c8a05833ce0ebe72194a350e@git.kernel.org>
Date:   Sat, 13 Jul 2019 04:08:44 -0700
From:   tip-bot for Leo Yan <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...nel.org,
        alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
        namhyung@...nel.org, leo.yan@...aro.org, ak@...ux.intel.com,
        linux-kernel@...r.kernel.org, mathieu.poirier@...aro.org,
        acme@...hat.com, suzuki.poulose@....com, hpa@...or.com,
        adrian.hunter@...el.com
Subject: [tip:perf/urgent] perf intel-bts: Fix potential NULL pointer
 dereference found by the smatch tool

Commit-ID:  1d481458816d9424c8a05833ce0ebe72194a350e
Gitweb:     https://git.kernel.org/tip/1d481458816d9424c8a05833ce0ebe72194a350e
Author:     Leo Yan <leo.yan@...aro.org>
AuthorDate: Mon, 8 Jul 2019 22:39:35 +0800
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Tue, 9 Jul 2019 10:13:28 -0300

perf intel-bts: Fix potential NULL pointer dereference found by the smatch tool

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         }

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

Signed-off-by: Leo Yan <leo.yan@...aro.org>
Acked-by: Adrian Hunter <adrian.hunter@...el.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Suzuki Poulouse <suzuki.poulose@....com>
Cc: linux-arm-kernel@...ts.infradead.org
Link: http://lkml.kernel.org/r/20190708143937.7722-3-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 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 5a21bcdb8ef7..5560e95afdda 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -891,13 +891,12 @@ int intel_bts_process_auxtrace_info(union perf_event *event,
 	if (dump_trace)
 		return 0;
 
-	if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
+	if (session->itrace_synth_opts->set) {
 		bts->synth_opts = *session->itrace_synth_opts;
 	} else {
 		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;
 	}