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

Arnaldo Carvalho de Melo
2019-07-09T18:32:29Z

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