From fa996c58e8a31ebe610d186cef408b6dd3b385a8 Mon Sep 17 00:00:00 2001
From: MarcoFalke <falke.marco@gmail.com>
Date: Mon, 1 Nov 2021 17:03:09 +0100
Subject: [PATCH] refactor: Avoid integer overflow in ApplyStats when
 activating snapshot

---
 src/index/coinstatsindex.cpp | 2 +-
 src/node/coinstats.cpp       | 5 ++++-
 src/node/coinstats.h         | 3 ++-
 src/rpc/blockchain.cpp       | 3 ++-
 4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/index/coinstatsindex.cpp b/src/index/coinstatsindex.cpp
index 9ab9209ca41..e4ee0e674b7 100644
--- a/src/index/coinstatsindex.cpp
+++ b/src/index/coinstatsindex.cpp
@@ -321,7 +321,7 @@ bool CoinStatsIndex::LookUpStats(const CBlockIndex* block_index, CCoinsStats& co
     coins_stats.hashSerialized = entry.muhash;
     coins_stats.nTransactionOutputs = entry.transaction_output_count;
     coins_stats.nBogoSize = entry.bogo_size;
-    coins_stats.nTotalAmount = entry.total_amount;
+    coins_stats.total_amount = entry.total_amount;
     coins_stats.total_subsidy = entry.total_subsidy;
     coins_stats.total_unspendable_amount = entry.total_unspendable_amount;
     coins_stats.total_prevout_spent_amount = entry.total_prevout_spent_amount;
diff --git a/src/node/coinstats.cpp b/src/node/coinstats.cpp
index 639a5791728..eb21bbdba85 100644
--- a/src/node/coinstats.cpp
+++ b/src/node/coinstats.cpp
@@ -11,6 +11,7 @@
 #include <index/coinstatsindex.h>
 #include <serialize.h>
 #include <uint256.h>
+#include <util/overflow.h>
 #include <util/system.h>
 #include <validation.h>
 
@@ -82,7 +83,9 @@ static void ApplyStats(CCoinsStats& stats, const uint256& hash, const std::map<u
     stats.nTransactions++;
     for (auto it = outputs.begin(); it != outputs.end(); ++it) {
         stats.nTransactionOutputs++;
-        stats.nTotalAmount += it->second.out.nValue;
+        if (stats.total_amount.has_value()) {
+            stats.total_amount = CheckedAdd(*stats.total_amount, it->second.out.nValue);
+        }
         stats.nBogoSize += GetBogoSize(it->second.out.scriptPubKey);
     }
 }
diff --git a/src/node/coinstats.h b/src/node/coinstats.h
index 1d95417d4fd..2a8fbf5bc64 100644
--- a/src/node/coinstats.h
+++ b/src/node/coinstats.h
@@ -35,7 +35,8 @@ struct CCoinsStats {
     uint64_t nBogoSize{0};
     uint256 hashSerialized{};
     uint64_t nDiskSize{0};
-    CAmount nTotalAmount{0};
+    //! The total amount, or nullopt if an overflow occurred calculating it
+    std::optional<CAmount> total_amount{0};
 
     //! The number of coins contained.
     uint64_t coins_count{0};
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 689c8751f33..f6112e78e07 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1244,7 +1244,8 @@ static RPCHelpMan gettxoutsetinfo()
         if (hash_type == CoinStatsHashType::MUHASH) {
             ret.pushKV("muhash", stats.hashSerialized.GetHex());
         }
-        ret.pushKV("total_amount", ValueFromAmount(stats.nTotalAmount));
+        CHECK_NONFATAL(stats.total_amount.has_value());
+        ret.pushKV("total_amount", ValueFromAmount(stats.total_amount.value()));
         if (!stats.index_used) {
             ret.pushKV("transactions", static_cast<int64_t>(stats.nTransactions));
             ret.pushKV("disk_size", stats.nDiskSize);