From 1825e37075aa7885930cb48c5452ba3e8952b78a Mon Sep 17 00:00:00 2001
From: Anthony Towns <aj@erisian.com.au>
Date: Wed, 27 Jun 2018 17:54:32 +1000
Subject: [PATCH] Error on missing amount in signrawtransaction*

Signatures using segregated witness commit to the amount being spent,
so that value must be passed into signrawtransactionwithkey and
signrawtransactionwithwallet. This ensures an error is issued if that
doesn't happen, rather than just assuming the value is 0 and producing
a signature that is almost certainly invalid.

Github-Pull: #13547
Rebased-From: a3b065b51fb333d976108a1fe34b7f663fd67285
---
 src/rpc/rawtransaction.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 82399e1567..3fbea1ff71 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -820,7 +820,7 @@ UniValue signrawtransaction(const JSONRPCRequest& request)
                 }
                 Coin newcoin;
                 newcoin.out.scriptPubKey = scriptPubKey;
-                newcoin.out.nValue = 0;
+                newcoin.out.nValue = MAX_MONEY;
                 if (prevOut.exists("amount")) {
                     newcoin.out.nValue = AmountFromValue(find_value(prevOut, "amount"));
                 }
@@ -898,6 +898,11 @@ UniValue signrawtransaction(const JSONRPCRequest& request)
 
         UpdateTransaction(mtx, i, sigdata);
 
+        // amount must be specified for valid segwit signature
+        if (amount == MAX_MONEY && !txin.scriptWitness.IsNull()) {
+            throw JSONRPCError(RPC_TYPE_ERROR, strprintf("Missing amount for %s", coin.out.ToString()));
+        }
+
         ScriptError serror = SCRIPT_ERR_OK;
         if (!VerifyScript(txin.scriptSig, prevPubKey, &txin.scriptWitness, STANDARD_SCRIPT_VERIFY_FLAGS, TransactionSignatureChecker(&txConst, i, amount), &serror)) {
             if (serror == SCRIPT_ERR_INVALID_STACK_OPERATION) {