[TD-6131]<fix> show vnodes crash

src/mnode/src/mnodeDnode.c

@@ -196,14 +196,20 @@ int32_t mnodeInitDnodes() {
   mnodeAddWriteMsgHandle(TSDB_MSG_TYPE_CM_CREATE_DNODE, mnodeProcessCreateDnodeMsg);
   mnodeAddWriteMsgHandle(TSDB_MSG_TYPE_CM_DROP_DNODE, mnodeProcessDropDnodeMsg); 
   mnodeAddWriteMsgHandle(TSDB_MSG_TYPE_CM_CONFIG_DNODE, mnodeProcessCfgDnodeMsg);
+
   mnodeAddPeerRspHandle(TSDB_MSG_TYPE_MD_CONFIG_DNODE_RSP, mnodeProcessCfgDnodeMsgRsp);
   mnodeAddPeerMsgHandle(TSDB_MSG_TYPE_DM_STATUS, mnodeProcessDnodeStatusMsg);
+
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_MODULE, mnodeGetModuleMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_MODULE, mnodeRetrieveModules);
+
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_VARIABLES, mnodeGetConfigMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_VARIABLES, mnodeRetrieveConfigs);
+
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_VNODES, mnodeGetVnodeMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_VNODES, mnodeRetrieveVnodes);
+  mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_VNODES, mnodeCancelGetNextVgroup);
+
   mnodeAddShowMetaHandle(TSDB_MGMT_TABLE_DNODE, mnodeGetDnodeMeta);
   mnodeAddShowRetrieveHandle(TSDB_MGMT_TABLE_DNODE, mnodeRetrieveDnodes);
   mnodeAddShowFreeIterHandle(TSDB_MGMT_TABLE_DNODE, mnodeCancelGetNextDnode);

src/mnode/src/mnodeShow.c

@@ -422,8 +422,13 @@ static void* mnodePutShowObj(SShowObj *pShow) {
 
 static void mnodeFreeShowObj(void *data) {
   SShowObj *pShow = *(SShowObj **)data;
-  if (tsMnodeShowFreeIterFp[pShow->type] != NULL && pShow->pIter != NULL) {
-    (*tsMnodeShowFreeIterFp[pShow->type])(pShow->pIter);
+  if (tsMnodeShowFreeIterFp[pShow->type] != NULL) {
+    if (pShow->pVgIter != NULL) {
+      // only used in 'show vnodes "ep"'
+      (*tsMnodeShowFreeIterFp[pShow->type])(pShow->pVgIter);
+    } else {
+      if (pShow->pIter != NULL) (*tsMnodeShowFreeIterFp[pShow->type])(pShow->pIter);
+    }
   }
 
   mDebug("%p, show is destroyed, data:%p index:%d", pShow, data, pShow->index);