From 57ec1c97b2d0c0ba6056a43fa4177efc39567ae2 Mon Sep 17 00:00:00 2001
From: Suhas Daftuar <sdaftuar@gmail.com>
Date: Mon, 30 Jul 2018 10:43:16 -0400
Subject: [wallet] correctly limit output group size

---
 src/wallet/wallet.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 4918100b30..ebf09a951a 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -4423,7 +4423,10 @@ std::vector<OutputGroup> CWallet::GroupOutputs(const std::vector<COutput>& outpu
             size_t ancestors, descendants;
             mempool.GetTransactionAncestry(output.tx->GetHash(), ancestors, descendants);
             if (!single_coin && ExtractDestination(output.tx->tx->vout[output.i].scriptPubKey, dst)) {
-                if (gmap.count(dst) == 10) {
+                // Limit output groups to no more than 10 entries, to protect
+                // against inadvertently creating a too-large transaction
+                // when using -avoidpartialspends
+                if (gmap[dst].m_outputs.size() >= 10) {
                     groups.push_back(gmap[dst]);
                     gmap.erase(dst);
                 }
-- 
cgit v1.2.3


From a13647b8bd667ca58d8e82682c1d46555dce42c9 Mon Sep 17 00:00:00 2001
From: Suhas Daftuar <sdaftuar@gmail.com>
Date: Mon, 30 Jul 2018 10:43:59 -0400
Subject: [qa] Add test for too-large wallet output groups

---
 test/functional/wallet_groups.py | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/test/functional/wallet_groups.py b/test/functional/wallet_groups.py
index 0d27815da0..408e9dfef0 100755
--- a/test/functional/wallet_groups.py
+++ b/test/functional/wallet_groups.py
@@ -5,6 +5,8 @@
 """Test wallet group functionality."""
 
 from test_framework.test_framework import BitcoinTestFramework
+from test_framework.mininode import FromHex, ToHex
+from test_framework.messages import CTransaction
 from test_framework.util import (
     assert_equal,
 )
@@ -63,5 +65,29 @@ class WalletGroupTest(BitcoinTestFramework):
         assert_approx(v[0], 0.2)
         assert_approx(v[1], 1.3, 0.0001)
 
+        # Empty out node2's wallet
+        self.nodes[2].sendtoaddress(address=self.nodes[0].getnewaddress(), amount=self.nodes[2].getbalance(), subtractfeefromamount=True)
+        self.sync_all()
+        self.nodes[0].generate(1)
+
+        # Fill node2's wallet with 10000 outputs corresponding to the same
+        # scriptPubKey
+        for i in range(5):
+            raw_tx = self.nodes[0].createrawtransaction([{"txid":"0"*64, "vout":0}], [{addr2[0]: 0.05}])
+            tx = FromHex(CTransaction(), raw_tx)
+            tx.vin = []
+            tx.vout = [tx.vout[0]] * 2000
+            funded_tx = self.nodes[0].fundrawtransaction(ToHex(tx))
+            signed_tx = self.nodes[0].signrawtransactionwithwallet(funded_tx['hex'])
+            self.nodes[0].sendrawtransaction(signed_tx['hex'])
+            self.nodes[0].generate(1)
+
+        self.sync_all()
+
+        # Check that we can create a transaction that only requires ~100 of our
+        # utxos, without pulling in all outputs and creating a transaction that
+        # is way too big.
+        assert self.nodes[2].sendtoaddress(address=addr2[0], amount=5)
+
 if __name__ == '__main__':
     WalletGroupTest().main ()
-- 
cgit v1.2.3