fix: invalid read while retrieve mnodes

source/dnode/mnode/impl/src/mndMnode.c

@@ -625,7 +625,7 @@ static int32_t mndRetrieveMnodes(SNodeMsg *pReq, SShowObj *pShow, SSDataBlock *p
     colDataAppend(pColInfo, numOfRows, b1, false);
 
     const char *roles = syncStr(pObj->role);
-    char       *b2 = taosMemoryCalloc(1, strlen(roles) + VARSTR_HEADER_SIZE);
+    char       *b2 = taosMemoryCalloc(1, strlen(roles) + 1 + VARSTR_HEADER_SIZE);
     STR_WITH_MAXSIZE_TO_VARSTR(b2, roles, pShow->pMeta->pSchemas[cols].bytes);
 
     pColInfo = taosArrayGet(pBlock->pDataBlock, cols++);

tests/script/tsim/show/basic.sim

@@ -3,9 +3,6 @@ system sh/deploy.sh -n dnode1 -i 1
 system sh/deploy.sh -n dnode2 -i 2
 system sh/exec.sh -n dnode1 -s start
 system sh/exec.sh -n dnode2 -s start
-
-# after mnode support, del sleep 2000, and check dnode status
-sleep 2000
 sql connect
 
 #$loop_cnt = 0