[PATCH 5/5] perf tools: Fix NULL pointer deference when vdso not found

[He Kuang]

We should check if 'dso' is a null pointer before passing it to the
function dso__type(), otherwise a segfault will be raised in
dso__data_get_fd(). In function machine__find_vdso(), the return value
checking of 'dso' is missed and this patch fixes this issue.

Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
---
 tools/perf/util/vdso.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
index 8f81c41..7bdcad4 100644
--- a/tools/perf/util/vdso.c
+++ b/tools/perf/util/vdso.c
@@ -296,7 +296,7 @@ static struct dso *machine__find_vdso(struct machine *machine,
 		if (!dso) {
 			dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
 					   true);
-			if (dso_type != dso__type(dso, machine))
+			if (dso && dso_type != dso__type(dso, machine))
 				dso = NULL;
 		}
 		break;
-- 
1.8.5.2