[PATCH] perf: cs-etm: Fix segfault in dso lookup

[James Clark]

map__dso() is called before thread__find_map() which always results in a
null pointer dereference. Fix it by finding first, then checking if it
exists.

Fixes: 63df0e4bc368 ("perf map: Add accessor for dso")
Signed-off-by: James Clark <james.clark at arm.com>
---
 tools/perf/util/cs-etm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 103865968700..8dd81ddd9e4e 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -885,9 +885,11 @@ static u32 cs_etm__mem_access(struct cs_etm_queue *etmq, u8 trace_chan_id,
 		thread = etmq->etm->unknown_thread;
 	}
 
-	dso = map__dso(al.map);
+	if (!thread__find_map(thread, cpumode, address, &al))
+		return 0;
 
-	if (!thread__find_map(thread, cpumode, address, &al) || !dso)
+	dso = map__dso(al.map);
+	if (!dso)
 		return 0;
 
 	if (dso->data.status == DSO_DATA_STATUS_ERROR &&
-- 
2.34.1