From 895528d1646feca076e75090bbffac492b9ee572 Mon Sep 17 00:00:00 2001
From: moruoxian <794997265moruoxian@gmail.com>
Date: Wed, 18 Jun 2025 12:59:01 +0800
Subject: [PATCH] fix: handle NULL json_str case to avoid undefined behavior

---
 plugins/mqtt/mqtt_handle.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/plugins/mqtt/mqtt_handle.c b/plugins/mqtt/mqtt_handle.c
index 45e74e397..44b083fa9 100644
--- a/plugins/mqtt/mqtt_handle.c
+++ b/plugins/mqtt/mqtt_handle.c
@@ -1491,7 +1491,9 @@ int handle_trans_data(neu_plugin_t *            plugin,
                 plugin, trans_data, plugin->config.format,
                 plugin->config.schema_vts, plugin->config.n_schema_vt,
                 static_tags, n_satic_tag, &skip_none);
-            size = strlen(json_str);
+            if (json_str != NULL) {
+                size = strlen(json_str);
+            }
         }
         if (n_satic_tag > 0) {
             mqtt_static_free(static_tags, n_satic_tag);