Merge bitcoin/bitcoin#23411: refactor: Avoid integer overflow in ApplyStats when activating snapshot

fa996c58e8a31ebe610d186cef408b6dd3b385a8 refactor: Avoid integer overflow in ApplyStats when activating snapshot (MarcoFalke)
fac01888d17423d6c23a9ce15d98fc88fb34e3cc Move AdditionOverflow to util, Add CheckedAdd with unit tests (MarcoFalke)
fa526d8fb6ab8f2678a30d4536aa9c45218f5269 Add dev doc to CCoinsStats::m_hash_type and make it const (MarcoFalke)
faff051560552d4405896e01920a18f698155a56 style: Remove unused whitespace (MarcoFalke)

Pull request description:

  A snapshot contains the utxo set, including the out value. To activate the snapshot, the hash needs to be calculated. As a side-effect, the total amount in the snapshot is calculated (as the sum of all out values), but never used. Instead of running into an integer overflow in an unused result, don't calculate the result in the first place.

  Other code paths (using the active utxo set) can not run into an integer overflow, since the active utxo set is valid.

  Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=39716

ACKs for top commit:
  shaavan:
    reACK fa996c58e8a31ebe610d186cef408b6dd3b385a8
  vasild:
    ACK fa996c58e8a31ebe610d186cef408b6dd3b385a8

Tree-SHA512: 4f207f634841f6f634fd02ae1e5907e343fd767524fd0e8149aa99fa9a1834fe50167d14874834d45236e9c325d567925f28129bacb7d80be29cf22277a16a14

7 files changed, 38 insertions, 11 deletions

diff --git a/src/test/fuzz/addition_overflow.cpp b/src/test/fuzz/addition_overflow.cpp
index c6cfbd8d30..cfad41659e 100644
--- a/src/test/fuzz/addition_overflow.cpp
+++ b/src/test/fuzz/addition_overflow.cpp
@@ -5,6 +5,7 @@
 #include <test/fuzz/FuzzedDataProvider.h>
 #include <test/fuzz/fuzz.h>
 #include <test/fuzz/util.h>
+#include <util/overflow.h>
 
 #include <cstdint>
 #include <string>
diff --git a/src/test/fuzz/crypto_chacha20_poly1305_aead.cpp b/src/test/fuzz/crypto_chacha20_poly1305_aead.cpp
index 5e60b0f25b..596614a71b 100644
--- a/src/test/fuzz/crypto_chacha20_poly1305_aead.cpp
+++ b/src/test/fuzz/crypto_chacha20_poly1305_aead.cpp
@@ -7,6 +7,7 @@
 #include <test/fuzz/FuzzedDataProvider.h>
 #include <test/fuzz/fuzz.h>
 #include <test/fuzz/util.h>
+#include <util/overflow.h>
 
 #include <cassert>
 #include <cstdint>
diff --git a/src/test/fuzz/integer.cpp b/src/test/fuzz/integer.cpp
index 33b0d7325b..3087f11771 100644
--- a/src/test/fuzz/integer.cpp
+++ b/src/test/fuzz/integer.cpp
@@ -26,6 +26,7 @@
 #include <univalue.h>
 #include <util/check.h>
 #include <util/moneystr.h>
+#include <util/overflow.h>
 #include <util/strencodings.h>
 #include <util/string.h>
 #include <util/system.h>
diff --git a/src/test/fuzz/pow.cpp b/src/test/fuzz/pow.cpp
index 1123c8c170..0004d82d66 100644
--- a/src/test/fuzz/pow.cpp
+++ b/src/test/fuzz/pow.cpp
@@ -9,6 +9,7 @@
 #include <test/fuzz/FuzzedDataProvider.h>
 #include <test/fuzz/fuzz.h>
 #include <test/fuzz/util.h>
+#include <util/overflow.h>
 
 #include <cstdint>
 #include <optional>
diff --git a/src/test/fuzz/util.cpp b/src/test/fuzz/util.cpp
index 843b29b911..5520eee758 100644
--- a/src/test/fuzz/util.cpp
+++ b/src/test/fuzz/util.cpp
@@ -8,6 +8,7 @@
 #include <pubkey.h>
 #include <test/fuzz/util.h>
 #include <test/util/script.h>
+#include <util/overflow.h>
 #include <util/rbf.h>
 #include <util/time.h>
 #include <version.h>
diff --git a/src/test/fuzz/util.h b/src/test/fuzz/util.h
index 7937315822..f4f8e9e70d 100644
--- a/src/test/fuzz/util.h
+++ b/src/test/fuzz/util.h
@@ -193,17 +193,6 @@ template <typename T>
     }
 }
 
-template <class T>
-[[nodiscard]] bool AdditionOverflow(const T i, const T j) noexcept
-{
-    static_assert(std::is_integral<T>::value, "Integral required.");
-    if (std::numeric_limits<T>::is_signed) {
-        return (i > 0 && j > std::numeric_limits<T>::max() - i) ||
-               (i < 0 && j < std::numeric_limits<T>::min() - i);
-    }
-    return std::numeric_limits<T>::max() - i < j;
-}
-
 [[nodiscard]] bool ContainsSpentInput(const CTransaction& tx, const CCoinsViewCache& inputs) noexcept;
 
 /**
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index 077d6e2d37..04c4524911 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -15,6 +15,7 @@
 #include <util/getuniquepath.h>
 #include <util/message.h> // For MessageSign(), MessageVerify(), MESSAGE_MAGIC
 #include <util/moneystr.h>
+#include <util/overflow.h>
 #include <util/spanparsing.h>
 #include <util/strencodings.h>
 #include <util/string.h>
@@ -1463,6 +1464,38 @@ BOOST_AUTO_TEST_CASE(test_IsDigit)
     BOOST_CHECK_EQUAL(IsDigit(9), false);
 }
 
+/* Check for overflow */
+template <typename T>
+static void TestAddMatrixOverflow()
+{
+    constexpr T MAXI{std::numeric_limits<T>::max()};
+    BOOST_CHECK(!CheckedAdd(T{1}, MAXI));
+    BOOST_CHECK(!CheckedAdd(MAXI, MAXI));
+    BOOST_CHECK_EQUAL(0, CheckedAdd(T{0}, T{0}).value());
+    BOOST_CHECK_EQUAL(MAXI, CheckedAdd(T{0}, MAXI).value());
+    BOOST_CHECK_EQUAL(MAXI, CheckedAdd(T{1}, MAXI - 1).value());
+}
+
+/* Check for overflow or underflow */
+template <typename T>
+static void TestAddMatrix()
+{
+    TestAddMatrixOverflow<T>();
+    constexpr T MINI{std::numeric_limits<T>::min()};
+    constexpr T MAXI{std::numeric_limits<T>::max()};
+    BOOST_CHECK(!CheckedAdd(T{-1}, MINI));
+    BOOST_CHECK(!CheckedAdd(MINI, MINI));
+    BOOST_CHECK_EQUAL(MINI, CheckedAdd(T{0}, MINI).value());
+    BOOST_CHECK_EQUAL(MINI, CheckedAdd(T{-1}, MINI + 1).value());
+    BOOST_CHECK_EQUAL(-1, CheckedAdd(MINI, MAXI).value());
+}
+
+BOOST_AUTO_TEST_CASE(util_overflow)
+{
+    TestAddMatrixOverflow<unsigned>();
+    TestAddMatrix<signed>();
+}
+
 BOOST_AUTO_TEST_CASE(test_ParseInt32)
 {
     int32_t n;