[PATCH v1 08/11] perf session: Smatch: Fix potential NULL pointer dereference

Leo Yan
2019-07-02T10:35:52Z

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>
---
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)
--
2.17.1