[PATCH] tests/qtest: Fix potential NULL pointer dereference in qos_build_main_args()

[AlexChen]

In qos_build_main_args(), the pointer 'path' is dereferenced before
checking it is valid, which may lead to NULL pointer dereference.
So move the assignment to 'cmd_line' after checking 'path' is valid.

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Alex Chen <alex.chen@huawei.com>
---
 tests/qtest/fuzz/qos_fuzz.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/qtest/fuzz/qos_fuzz.c b/tests/qtest/fuzz/qos_fuzz.c
index b943577b8c..cee1a2a60f 100644
--- a/tests/qtest/fuzz/qos_fuzz.c
+++ b/tests/qtest/fuzz/qos_fuzz.c
@@ -70,7 +70,7 @@ static GString *qos_build_main_args(void)
 {
     char **path = fuzz_path_vec;
     QOSGraphNode *test_node;
-    GString *cmd_line = g_string_new(path[0]);
+    GString *cmd_line;
     void *test_arg;

     if (!path) {
@@ -79,6 +79,7 @@ static GString *qos_build_main_args(void)
     }

     /* Before test */
+    cmd_line = g_string_new(path[0]);
     current_path = path;
     test_node = qos_graph_get_node(path[(g_strv_length(path) - 1)]);
     test_arg = test_node->u.test.arg;
-- 
2.19.1