[PATCH] perf evsel: fix NULL pointer deference when evsel->counts is NULL

[Colin King]

From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

__perf_evsel__read_on_cpu() only bails out with -ENOMEM if
evsel->counts is NULL and perf_evsel__alloc_counts() has returned
an error.  If perf_evsel__alloc_counts() does not return an error
we get an NULL pointer deference on evsel->counts->cpu[cpu]
if evsel->counts is NULL.

Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
---
 tools/perf/util/evsel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 1b16dd1..93acd06 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -640,7 +640,7 @@ int __perf_evsel__read_on_cpu(struct perf_evsel *evsel,
 	if (FD(evsel, cpu, thread) < 0)
 		return -EINVAL;
 
-	if (evsel->counts == NULL && perf_evsel__alloc_counts(evsel, cpu + 1) < 0)
+	if (evsel->counts == NULL || perf_evsel__alloc_counts(evsel, cpu + 1) < 0)
 		return -ENOMEM;
 
 	if (readn(FD(evsel, cpu, thread), &count, nv * sizeof(u64)) < 0)
-- 
1.8.0

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