From c3339b5ba1fb2c48d2c99a310f5a46e682459901 Mon Sep 17 00:00:00 2001
From: openGaussDev <lvyongjian@huawei.com>
Date: Thu, 10 Mar 2022 10:21:28 +0800
Subject: [PATCH]  fix invalid memory in undo

Offering: openGaussDev

More detail: fix invalid memory in undo

Match-id-496852205f7ba0be46bf71ec29580aeece9d50f5
---
 .../storage/access/ustore/knl_undoaction.cpp   | 18 ++++++++++--------
 .../storage/access/ustore/knl_uundovec.cpp     |  2 +-
 src/include/access/ustore/knl_undorequest.h    |  3 +++
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/gausskernel/storage/access/ustore/knl_undoaction.cpp b/src/gausskernel/storage/access/ustore/knl_undoaction.cpp
index 0c285a90a..b82f02313 100644
--- a/src/gausskernel/storage/access/ustore/knl_undoaction.cpp
+++ b/src/gausskernel/storage/access/ustore/knl_undoaction.cpp
@@ -35,6 +35,14 @@ static UHeapDiskTuple CopyTupleFromUndoRecord(Relation relation, UndoRecord *und
 static void RestoreXactFromUndoRecord(UndoRecord *undorecord, Buffer buffer, UHeapDiskTuple tuple);
 static void LogUHeapUndoActions(UHeapUndoActionWALInfo *walInfo, Relation rel);
 
+static int GetUndoApplySize()
+{
+    uint64 undoApplySize = (uint64)u_sess->attr.attr_memory.maintenance_work_mem * 1024L;
+    uint64 applySize = MAX_UNDO_APPLY_SIZE > undoApplySize ? undoApplySize : MAX_UNDO_APPLY_SIZE;
+    Assert(applySize <= MAX_UNDO_APPLY_SIZE);
+    return (int)applySize;
+}
+
 /*
  * execute_undo_actions - Execute the undo actions
  *
@@ -49,10 +57,7 @@ void ExecuteUndoActions(TransactionId fullXid, UndoRecPtr fromUrecptr, UndoRecPt
     Assert(toUrecptr != INVALID_UNDO_REC_PTR && fromUrecptr != INVALID_UNDO_REC_PTR);
     Assert(slotPtr != INVALID_UNDO_REC_PTR);
     Assert(fullXid  != InvalidTransactionId);
-    int undoApplySize = u_sess->attr.attr_memory.maintenance_work_mem * 1024L;
-
-    /* setting maintenance_work_mem atleast 2GB will cause an overflow */
-    undoApplySize = (undoApplySize < 0) ? INT_MAX : undoApplySize;
+    int undoApplySize = GetUndoApplySize();
     UndoRecPtr urecPtr = fromUrecptr;
     UndoRecord *urec = New(CurrentMemoryContext)UndoRecord();
     urec->SetUrp(toUrecptr);
@@ -165,10 +170,7 @@ void ExecuteUndoActions(TransactionId fullXid, UndoRecPtr fromUrecptr, UndoRecPt
 void ExecuteUndoActionsPage(UndoRecPtr fromUrp, Relation rel, Buffer buffer, TransactionId xid)
 {
     UndoRecPtr urp = fromUrp;
-    int undoApplySize = u_sess->attr.attr_memory.maintenance_work_mem * 1024L;
-
-    /* setting maintenance_work_mem atleast 2GB will cause an overflow */
-    undoApplySize = (undoApplySize < 0) ? INT_MAX : undoApplySize;
+    int undoApplySize = GetUndoApplySize();
 
     /*
      * Fetch the multiple undo records which can fit into undoApplySize;
diff --git a/src/gausskernel/storage/access/ustore/knl_uundovec.cpp b/src/gausskernel/storage/access/ustore/knl_uundovec.cpp
index 8d72ae7b5..e8e101a29 100644
--- a/src/gausskernel/storage/access/ustore/knl_uundovec.cpp
+++ b/src/gausskernel/storage/access/ustore/knl_uundovec.cpp
@@ -480,7 +480,7 @@ URecVector* FetchUndoRecordRange(    __inout UndoRecPtr *startUrp,
         }
 
         totalSize += urec->MemoryRecordSize();
-        if (totalSize > maxUndoApplySize) {
+        if (totalSize >= maxUndoApplySize) {
             *startUrp = currUrp;
             break;
         }
diff --git a/src/include/access/ustore/knl_undorequest.h b/src/include/access/ustore/knl_undorequest.h
index 6380b0249..a22f9f2c3 100644
--- a/src/include/access/ustore/knl_undorequest.h
+++ b/src/include/access/ustore/knl_undorequest.h
@@ -21,6 +21,9 @@
 #include "access/ustore/knl_uundovec.h"
 #include "utils/rel.h"
 
+/* Maximum size of the cache of undo records in a single rollback, 64M. */
+const uint64 MAX_UNDO_APPLY_SIZE = 64 * 1024 * 1024;
+
 typedef struct RollbackRequestsHashKey {
     TransactionId xid;
     UndoRecPtr startUndoPtr;