Merge #17156: psbt: check that various indexes and amounts are within bounds

deaa6dd144f5650b385658a0c4f9a014aff8dde2 psbt: check output index is within bounds before accessing (Andrew Chow)
f1ef7f0aa46338f4cd8de79696027a1bf868f359 Don't calculate tx fees for PSBTs with invalid money values (Andrew Chow)

Pull request description:

  Fixes #17149

  Two classes of issues were found by the psbt fuzzer: values out of range and causing overflows, and prevout indexes being out of range. This PR fixes both.

  When accessing a specific output using the index given in the tx, check that it is actually a possible output before trying to access the output.

  When summing and checking amounts for `decodepsbt` and `analyzepsbt`, make sure that the values are actually valid money values.. Otherwise, stop summing and don't show the fee. For `analyzepsbt`, return that the next role is the Creator since the Creator needs to remake the transaction to be valid.

ACKs for top commit:
  practicalswift:
    ACK deaa6dd144f5650b385658a0c4f9a014aff8dde2 -- only change since last ACK was the addition of tests
  gwillen:
    tested ACK deaa6dd, would also like to see this merged!

Tree-SHA512: 06c36720bbb5a7ab1c29f7d15878bf9f0d3e5760c06bff479d412e1bf07bb3e0e9ab6cca820a4bfedaab71bfd7af813807e87cbcdf0af25cc3f66a53a06dbcfd

1 files changed, 19 insertions, 3 deletions

diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 5be7acce1c..cea59b2c7a 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -1079,7 +1079,12 @@ UniValue decodepsbt(const JSONRPCRequest& request)
             UniValue out(UniValue::VOBJ);
 
             out.pushKV("amount", ValueFromAmount(txout.nValue));
-            total_in += txout.nValue;
+            if (MoneyRange(txout.nValue) && MoneyRange(total_in + txout.nValue)) {
+                total_in += txout.nValue;
+            } else {
+                // Hack to just not show fee later
+                have_all_utxos = false;
+            }
 
             UniValue o(UniValue::VOBJ);
             ScriptToUniv(txout.scriptPubKey, o, true);
@@ -1089,7 +1094,13 @@ UniValue decodepsbt(const JSONRPCRequest& request)
             UniValue non_wit(UniValue::VOBJ);
             TxToUniv(*input.non_witness_utxo, uint256(), non_wit, false);
             in.pushKV("non_witness_utxo", non_wit);
-            total_in += input.non_witness_utxo->vout[psbtx.tx->vin[i].prevout.n].nValue;
+            CAmount utxo_val = input.non_witness_utxo->vout[psbtx.tx->vin[i].prevout.n].nValue;
+            if (MoneyRange(utxo_val) && MoneyRange(total_in + utxo_val)) {
+                total_in += utxo_val;
+            } else {
+                // Hack to just not show fee later
+                have_all_utxos = false;
+            }
         } else {
             have_all_utxos = false;
         }
@@ -1205,7 +1216,12 @@ UniValue decodepsbt(const JSONRPCRequest& request)
         outputs.push_back(out);
 
         // Fee calculation
-        output_value += psbtx.tx->vout[i].nValue;
+        if (MoneyRange(psbtx.tx->vout[i].nValue) && MoneyRange(output_value + psbtx.tx->vout[i].nValue)) {
+            output_value += psbtx.tx->vout[i].nValue;
+        } else {
+            // Hack to just not show fee later
+            have_all_utxos = false;
+        }
     }
     result.pushKV("outputs", outputs);
     if (have_all_utxos) {