Merge #14248: [0.17] Fix crash bug with duplicate inputs within a transaction

0d49c82 [qa] backport: Test for duplicate inputs within a transaction (Suhas Daftuar)
833180f Fix crash bug with duplicate inputs within a transaction (Suhas Daftuar)

Pull request description:

  This is a backport of #14247.

Tree-SHA512: 4d3b6244d501a48f56a728c571dac9a346019a671434edac943f4f535ef8f94ec6bfd569a0585ad5e23a6e488ecd7e0079510cbb10a2a22f576eb36d73accb0c

Author: laanwj

src/validation.cpp

@@ -3130,7 +3130,7 @@ bool CheckBlock(const CBlock& block, CValidationState& state, const Consensus::P
 
     // Check transactions
     for (const auto& tx : block.vtx)
-        if (!CheckTransaction(*tx, state, false))
+        if (!CheckTransaction(*tx, state, true))
             return state.Invalid(false, state.GetRejectCode(), state.GetRejectReason(),
                                  strprintf("Transaction check failed (tx hash %s) %s", tx->GetHash().ToString(), state.GetDebugMessage()));
 

test/functional/p2p_invalid_block.py

@@ -81,6 +81,16 @@ def run_test(self):
 
         node.p2p.send_blocks_and_test([block2], node, False, False, 16, b'bad-txns-duplicate')
 
+        # Check transactions for duplicate inputs
+        self.log.info("Test duplicate input block.")
+
+        block2_orig.vtx[2].vin.append(block2_orig.vtx[2].vin[0])
+        block2_orig.vtx[2].rehash()
+        block2_orig.hashMerkleRoot = block2_orig.calc_merkle_root()
+        block2_orig.rehash()
+        block2_orig.solve()
+        node.p2p.send_blocks_and_test([block2_orig], node, success=False, request_block=False, reject_reason=b'bad-txns-inputs-duplicate')
+
         self.log.info("Test very broken block.")
 
         block3 = create_block(tip, create_coinbase(height), block_time)