lib/test: use after free in register_test_dev_kmod()

The "test_dev" pointer is freed but then returned to the caller.

Fixes: d9c6a72d6f ("kmod: add test driver to stress test the module loader")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

lib/test_kmod.c

@@ -1149,6 +1149,7 @@ static struct kmod_test_device *register_test_dev_kmod(void)
 	if (ret) {
 		pr_err("could not register misc device: %d\n", ret);
 		free_test_dev_kmod(test_dev);
+		test_dev = NULL;
 		goto out;
 	}