From 5feb4106abbe845698fbe969d78cfbf0c04cc0c4 Mon Sep 17 00:00:00 2001
From: wangmm0220 <wangmm0220@gmail.com>
Date: Fri, 27 Aug 2021 18:17:35 +0800
Subject: [PATCH] [TD-6167]<fix> add null pointer protection

---
 src/client/src/tscPrepare.c | 7 +++++--
 tests/script/api/stmt.c     | 1 +
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/client/src/tscPrepare.c b/src/client/src/tscPrepare.c
index 36dd60c4fe..3b13f6435d 100644
--- a/src/client/src/tscPrepare.c
+++ b/src/client/src/tscPrepare.c
@@ -1783,7 +1783,9 @@ int taos_stmt_set_tbname(TAOS_STMT* stmt, const char* name) {
 
 int taos_stmt_close(TAOS_STMT* stmt) {
   STscStmt* pStmt = (STscStmt*)stmt;
-  STMT_CHECK
+  if (pStmt == NULL || pStmt->taos == NULL) {
+    STMT_RET(TSDB_CODE_TSC_DISCONNECTED);
+  }
   if (!pStmt->isInsert) {
     SNormalStmt* normal = &pStmt->normal;
     if (normal->params != NULL) {
@@ -1812,7 +1814,7 @@ int taos_stmt_close(TAOS_STMT* stmt) {
     }
   }
 
-  tscFreeSqlObj(pStmt->pSql);
+  taos_free_result(pStmt->pSql);
   tfree(pStmt);
   STMT_RET(TSDB_CODE_SUCCESS);
 }
@@ -1986,6 +1988,7 @@ TAOS_RES *taos_stmt_use_result(TAOS_STMT* stmt) {
     return NULL;
   }
   TAOS_RES* result = pStmt->pSql;
+  pStmt->pSql = NULL;
   return result;
 }
 
diff --git a/tests/script/api/stmt.c b/tests/script/api/stmt.c
index 168d281f70..baf40c1421 100644
--- a/tests/script/api/stmt.c
+++ b/tests/script/api/stmt.c
@@ -465,6 +465,7 @@ void taos_stmt_use_result_query(void *taos, char *col, int type) {
   TAOS_RES *result = taos_stmt_use_result(stmt);
   assert(result != NULL);
   print_result(result);
+  taos_free_result(result);
   assert(taos_stmt_close(stmt) == 0);
   free(params);
   free(stmt_sql);
-- 
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