[PATCH 08/25] perf session: Fix potential NULL pointer dereference found by the smatch tool

From: Arnaldo Carvalho de Melo <acme@kernel•org>
To: Ingo Molnar <mingo@kernel•org>, Thomas Gleixner <tglx@linutronix•de>
Cc: Song Liu <songliubraving@fb•com>,
	Konstantin Khlebnikov <khlebnikov@yandex-team•ru>,
	Rasmus Villemoes <linux@rasmusvillemoes•dk>,
	Adrian Hunter <adrian.hunter@intel•com>,
	Jin Yao <yao.jin@linux•intel.com>,
	Andi Kleen <ak@linux•intel.com>,
	Alexey Budankov <alexey.budankov@linux•intel.com>,
	Clark Williams <williams@redhat•com>,
	Suzuki Poulouse <suzuki.poulose@arm•com>,
	Arnaldo Carvalho de Melo <acme@redhat•com>,
	Alexios Zavras <alexios.zavras@intel•com>,
	Davidlohr Bueso <dave@stgolabs•net>,
	Namhyung Kim <namhyung@kernel•org>,
	linux-arm-kernel@lists•infradead.org,
	Mathieu Poirier <mathieu.poirier@linaro•org>,
	Thomas Richter <tmricht@linux•ibm.com>,
	linux-kernel@vger•kernel.org,
	Alexander Shishkin <alexander.shishkin@linux•intel.com>,
	"David S . Miller" <davem@davemloft•net>,
	linux-perf-users@vger•kernel.org,
	Changbin Du <changbin.du@intel•com>,
	Peter Zijlstra <peterz@infradead•org>,
	Jiri Olsa <jolsa@kernel•org>, Leo Yan <leo.yan@linaro•org>,
	Eric Saint-Etienne <eric.saint.etienne@oracle•com>
Subject: [PATCH 08/25] perf session: Fix potential NULL pointer dereference found by the smatch tool
Date: Tue,  9 Jul 2019 15:31:09 -0300	[thread overview]
Message-ID: <20190709183126.30257-9-acme@kernel.org> (raw)
In-Reply-To: <20190709183126.30257-1-acme@kernel.org>

From: Leo Yan <leo.yan@linaro•org>

Based on the following report from Smatch, fix the potential
NULL pointer dereference check.

  tools/perf/util/session.c:1252
  dump_read() error: we previously assumed 'evsel' could be null
  (see line 1249)

  tools/perf/util/session.c
  1240 static void dump_read(struct perf_evsel *evsel, union perf_event *event)
  1241 {
  1242         struct read_event *read_event = &event->read;
  1243         u64 read_format;
  1244
  1245         if (!dump_trace)
  1246                 return;
  1247
  1248         printf(": %d %d %s %" PRIu64 "\n", event->read.pid, event->read.tid,
  1249                evsel ? perf_evsel__name(evsel) : "FAIL",
  1250                event->read.value);
  1251
  1252         read_format = evsel->attr.read_format;
                             ^^^^^^^

'evsel' could be NULL pointer, for this case this patch directly bails
out without dumping read_event.

Signed-off-by: Leo Yan <leo.yan@linaro•org>
Acked-by: Jiri Olsa <jolsa@kernel•org>
Cc: Adrian Hunter <adrian.hunter@intel•com>
Cc: Alexander Shishkin <alexander.shishkin@linux•intel.com>
Cc: Alexey Budankov <alexey.budankov@linux•intel.com>
Cc: Alexios Zavras <alexios.zavras@intel•com>
Cc: Andi Kleen <ak@linux•intel.com>
Cc: Changbin Du <changbin.du@intel•com>
Cc: David S. Miller <davem@davemloft•net>
Cc: Davidlohr Bueso <dave@stgolabs•net>
Cc: Eric Saint-Etienne <eric.saint.etienne@oracle•com>
Cc: Jin Yao <yao.jin@linux•intel.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team•ru>
Cc: Mathieu Poirier <mathieu.poirier@linaro•org>
Cc: Namhyung Kim <namhyung@kernel•org>
Cc: Peter Zijlstra <peterz@infradead•org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes•dk>
Cc: Song Liu <songliubraving@fb•com>
Cc: Suzuki Poulouse <suzuki.poulose@arm•com>
Cc: Thomas Gleixner <tglx@linutronix•de>
Cc: Thomas Richter <tmricht@linux•ibm.com>
Cc: linux-arm-kernel@lists•infradead.org
Link: http://lkml.kernel.org/r/20190702103420.27540-9-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat•com>
---
 tools/perf/util/session.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 54cf163347f7..2e61dd6a3574 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1249,6 +1249,9 @@ static void dump_read(struct perf_evsel *evsel, union perf_event *event)
 	       evsel ? perf_evsel__name(evsel) : "FAIL",
 	       event->read.value);
 
+	if (!evsel)
+		return;
+
 	read_format = evsel->attr.read_format;
 
 	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
-- 
2.21.0


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