linux-kernel - [PATCH AUTOSEL 5.2 133/171] perf intel-bts: Fix potential NULL pointer dereference found by the smatch tool

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Message-Id: <20190719035643.14300-133-sashal@kernel.org>
Date:   Thu, 18 Jul 2019 23:56:04 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Leo Yan <leo.yan@...aro.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>, Jiri Olsa <jolsa@...hat.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Suzuki Poulouse <suzuki.poulose@....com>,
        linux-arm-kernel@...ts.infradead.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.2 133/171] perf intel-bts: Fix potential NULL pointer dereference found by the smatch tool

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

[ Upstream commit 1d481458816d9424c8a05833ce0ebe72194a350e ]

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>
Signed-off-by: Sasha Levin <sashal@...nel.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..625ad3639a7e 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;
 	}
 
-- 
2.20.1