Avoid leaking prioritization information when relaying transactions

Author: sdaftuar

src/txmempool.h

@@ -241,15 +241,18 @@ class CompareTxMemPoolEntryByDescendantScore
 
 /** \class CompareTxMemPoolEntryByScore
  *
- *  Sort by score of entry ((fee+delta)/size) in descending order
+ *  Sort by feerate of entry (fee/size) in descending order
+ *  This is only used for transaction relay, so we use GetFee()
+ *  instead of GetModifiedFee() to avoid leaking prioritization
+ *  information via the sort order.
  */
 class CompareTxMemPoolEntryByScore
 {
 public:
     bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b) const
     {
-        double f1 = (double)a.GetModifiedFee() * b.GetTxSize();
-        double f2 = (double)b.GetModifiedFee() * a.GetTxSize();
+        double f1 = (double)a.GetFee() * b.GetTxSize();
+        double f2 = (double)b.GetFee() * a.GetTxSize();
         if (f1 == f2) {
             return b.GetTx().GetHash() < a.GetTx().GetHash();
         }