fix(query): fix invalid read in doModeAdd

TD-19124

source/libs/function/src/builtinsimpl.c

@@ -5297,12 +5297,12 @@ bool modeFunctionSetup(SqlFunctionCtx* pCtx, SResultRowEntryInfo* pResInfo) {
 }
 
 static void doModeAdd(SModeInfo* pInfo, char* data) {
-  int32_t     hashKeyBytes = IS_VAR_DATA_TYPE(pInfo->colType) ? varDataTLen(data) : pInfo->colBytes;
+  int32_t     hashKeyBytes = IS_STR_DATA_TYPE(pInfo->colType) ? varDataTLen(data) : pInfo->colBytes;
   SModeItem** pHashItem = taosHashGet(pInfo->pHash, data, hashKeyBytes);
   if (pHashItem == NULL) {
     int32_t    size = sizeof(SModeItem) + pInfo->colBytes;
     SModeItem* pItem = (SModeItem*)(pInfo->pItems + pInfo->numOfPoints * size);
-    memcpy(pItem->data, data, pInfo->colBytes);
+    memcpy(pItem->data, data, hashKeyBytes);
     pItem->count += 1;
 
     taosHashPut(pInfo->pHash, data, hashKeyBytes, &pItem, sizeof(SModeItem*));