diff --git a/source/common/src/tdatablock.c b/source/common/src/tdatablock.c
index 3021c586a364ff61e3b46439cdb2093f4c307287..1ae8dafcf347c2619f26433bef4408900b57eabe 100644
--- a/source/common/src/tdatablock.c
+++ b/source/common/src/tdatablock.c
@@ -509,8 +509,12 @@ SSDataBlock* blockDataExtractBlock(SSDataBlock* pBlock, int32_t startIndex, int3
         isNull = colDataIsNull(pColData, pBlock->info.rows, j, pBlock->pBlockAgg[i]);
       }
 
-      char* p = colDataGetData(pColData, j);
-      colDataAppend(pDstCol, j - startIndex, p, isNull);
+      if (isNull) {
+        colDataAppendNULL(pDstCol, j - startIndex);
+      } else {
+        char* p = colDataGetData(pColData, j);
+        colDataAppend(pDstCol, j - startIndex, p, false);
+      }
     }
   }
 
@@ -807,7 +811,9 @@ static int32_t blockDataAssign(SColumnInfoData* pCols, const SSDataBlock* pDataB
     SColumnInfoData* pSrc = taosArrayGet(pDataBlock->pDataBlock, i);
 
     if (IS_VAR_DATA_TYPE(pSrc->info.type)) {
-      memcpy(pDst->pData, pSrc->pData, pSrc->varmeta.length);
+      if (pSrc->varmeta.length != 0) {
+        memcpy(pDst->pData, pSrc->pData, pSrc->varmeta.length);
+      }
       pDst->varmeta.length = pSrc->varmeta.length;
 
       for (int32_t j = 0; j < pDataBlock->info.rows; ++j) {
diff --git a/tests/script/sh/checkAsan.sh b/tests/script/sh/checkAsan.sh
index aa0f5b6b7643131aa63e36f764bd5d42142a49cd..7df17b22da1c8a8c3b7cf95315a3aea417d56eae 100755
--- a/tests/script/sh/checkAsan.sh
+++ b/tests/script/sh/checkAsan.sh
@@ -59,4 +59,4 @@ else
   fi
   cat ${LOG_DIR}/*.asan
   exit 1
-fi
\ No newline at end of file
+fi