psbt: Check non witness utxo outpoint early

A common issue that our fuzzers keep finding is that outpoints don't
exist in the non witness utxos. Instead of trying to track this down and
checking in various individual places, do the check early during
deserialization.

Author: achow101

src/psbt.h

@@ -1173,8 +1173,13 @@ struct PartiallySignedTransaction
             inputs.push_back(input);
 
             // Make sure the non-witness utxo matches the outpoint
-            if (input.non_witness_utxo && input.non_witness_utxo->GetHash() != tx->vin[i].prevout.hash) {
-                throw std::ios_base::failure("Non-witness UTXO does not match outpoint hash");
+            if (input.non_witness_utxo) {
+                if (input.non_witness_utxo->GetHash() != tx->vin[i].prevout.hash) {
+                    throw std::ios_base::failure("Non-witness UTXO does not match outpoint hash");
+                }
+                if (tx->vin[i].prevout.n >= input.non_witness_utxo->vout.size()) {
+                    throw std::ios_base::failure("Input specifies output index that does not exist");
+                }
             }
             ++i;
         }

test/functional/data/rpc_psbt.json

@@ -38,7 +38,9 @@
         "cHNidP8BAF4CAAAAAZvUh2UjC/mnLmYgAflyVW5U8Mb5f+tWvLVgDYF/aZUmAQAAAAD/////AUjmBSoBAAAAIlEgAw2k/OT32yjCyylRYx4ANxOFZZf+ljiCy1AOaBEsymMAAAAAAAEBKwDyBSoBAAAAIlEgwiR++/2SrEf29AuNQtFpF1oZ+p+hDkol1/NetN2FtpJBFCyxOsaCSN6AaqajZZzzwD62gh0JyBFKToaP696GW7bSzZcOFfU/wMgvlQ/VYP+pGbdhcr4Bc2iomROvB09ACwlCiXVqo3OczGiewPzzo2C+MswLWbFuk6Hou0YFcmssp6P/cGxBdmSWMrLMaOH5ErileONxnOdxCIXHqWb0m81DywEBAAA=",
         "cHNidP8BAF4CAAAAAZvUh2UjC/mnLmYgAflyVW5U8Mb5f+tWvLVgDYF/aZUmAQAAAAD/////AUjmBSoBAAAAIlEgAw2k/OT32yjCyylRYx4ANxOFZZf+ljiCy1AOaBEsymMAAAAAAAEBKwDyBSoBAAAAIlEgwiR++/2SrEf29AuNQtFpF1oZ+p+hDkol1/NetN2FtpJBFCyxOsaCSN6AaqajZZzzwD62gh0JyBFKToaP696GW7bSzZcOFfU/wMgvlQ/VYP+pGbdhcr4Bc2iomROvB09ACwk5iXVqo3OczGiewPzzo2C+MswLWbFuk6Hou0YFcmssp6P/cGxBdmSWMrLMaOH5ErileONxnOdxCIXHqWb0m81DywAA",
         "cHNidP8BAF4CAAAAAZvUh2UjC/mnLmYgAflyVW5U8Mb5f+tWvLVgDYF/aZUmAQAAAAD/////AUjmBSoBAAAAIlEgAw2k/OT32yjCyylRYx4ANxOFZZf+ljiCy1AOaBEsymMAAAAAAAEBKwDyBSoBAAAAIlEgwiR++/2SrEf29AuNQtFpF1oZ+p+hDkol1/NetN2FtpJjFcFQkpt0waBJVLeLS2A16XpeB4paDyjsltVHv+6azoA6wG99YgWelJehpKJnVp2YdtpgEBr/OONSm5uTnOf5GulwEV8uSQr3zEXE94UR82BXzlxaXFYyWin7RN/CA/NW4fgAIyAssTrGgkjegGqmo2Wc88A+toIdCcgRSk6Gj+vehlu20qzAAAA=",
-        "cHNidP8BAF4CAAAAAZvUh2UjC/mnLmYgAflyVW5U8Mb5f+tWvLVgDYF/aZUmAQAAAAD/////AUjmBSoBAAAAIlEgAw2k/OT32yjCyylRYx4ANxOFZZf+ljiCy1AOaBEsymMAAAAAAAEBKwDyBSoBAAAAIlEgwiR++/2SrEf29AuNQtFpF1oZ+p+hDkol1/NetN2FtpJhFcFQkpt0waBJVLeLS2A16XpeB4paDyjsltVHv+6azoA6wG99YgWelJehpKJnVp2YdtpgEBr/OONSm5uTnOf5GulwEV8uSQr3zEXE94UR82BXzlxaXFYyWin7RN/CA/NW4SMgLLE6xoJI3oBqpqNlnPPAPraCHQnIEUpOho/r3oZbttKswAAA"
+        "cHNidP8BAF4CAAAAAZvUh2UjC/mnLmYgAflyVW5U8Mb5f+tWvLVgDYF/aZUmAQAAAAD/////AUjmBSoBAAAAIlEgAw2k/OT32yjCyylRYx4ANxOFZZf+ljiCy1AOaBEsymMAAAAAAAEBKwDyBSoBAAAAIlEgwiR++/2SrEf29AuNQtFpF1oZ+p+hDkol1/NetN2FtpJhFcFQkpt0waBJVLeLS2A16XpeB4paDyjsltVHv+6azoA6wG99YgWelJehpKJnVp2YdtpgEBr/OONSm5uTnOf5GulwEV8uSQr3zEXE94UR82BXzlxaXFYyWin7RN/CA/NW4SMgLLE6xoJI3oBqpqNlnPPAPraCHQnIEUpOho/r3oZbttKswAAA",
+        "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",
+        "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"
     ],
     "invalid_with_msg": [
         [

test/functional/rpc_psbt.py

@@ -701,11 +701,9 @@ def test_psbt_input_keys(psbt_input, keys):
         assert_equal(analysis['next'], 'creator')
         assert_equal(analysis['error'], 'PSBT is not valid. Output amount invalid')
 
-        analysis = self.nodes[0].analyzepsbt('cHNidP8BAJoCAAAAAkvEW8NnDtdNtDpsmze+Ht2LH35IJcKv00jKAlUs21RrAwAAAAD/////S8Rbw2cO1020OmybN74e3Ysffkglwq/TSMoCVSzbVGsBAAAAAP7///8CwLYClQAAAAAWABSNJKzjaUb3uOxixsvh1GGE3fW7zQD5ApUAAAAAFgAUKNw0x8HRctAgmvoevm4u1SbN7XIAAAAAAAEAnQIAAAACczMa321tVHuN4GKWKRncycI22aX3uXgwSFUKM2orjRsBAAAAAP7///9zMxrfbW1Ue43gYpYpGdzJwjbZpfe5eDBIVQozaiuNGwAAAAAA/v///wIA+QKVAAAAABl2qRT9zXUVA8Ls5iVqynLHe5/vSe1XyYisQM0ClQAAAAAWABRmWQUcjSjghQ8/uH4Bn/zkakwLtAAAAAAAAQEfQM0ClQAAAAAWABRmWQUcjSjghQ8/uH4Bn/zkakwLtAAAAA==')
-        assert_equal(analysis['next'], 'creator')
-        assert_equal(analysis['error'], 'PSBT is not valid. Input 0 specifies invalid prevout')
+        assert_raises_rpc_error(-22, "TX decode failed", self.nodes[0].analyzepsbt, "cHNidP8BAJoCAAAAAkvEW8NnDtdNtDpsmze+Ht2LH35IJcKv00jKAlUs21RrAwAAAAD/////S8Rbw2cO1020OmybN74e3Ysffkglwq/TSMoCVSzbVGsBAAAAAP7///8CwLYClQAAAAAWABSNJKzjaUb3uOxixsvh1GGE3fW7zQD5ApUAAAAAFgAUKNw0x8HRctAgmvoevm4u1SbN7XIAAAAAAAEAnQIAAAACczMa321tVHuN4GKWKRncycI22aX3uXgwSFUKM2orjRsBAAAAAP7///9zMxrfbW1Ue43gYpYpGdzJwjbZpfe5eDBIVQozaiuNGwAAAAAA/v///wIA+QKVAAAAABl2qRT9zXUVA8Ls5iVqynLHe5/vSe1XyYisQM0ClQAAAAAWABRmWQUcjSjghQ8/uH4Bn/zkakwLtAAAAAAAAQEfQM0ClQAAAAAWABRmWQUcjSjghQ8/uH4Bn/zkakwLtAAAAA==")
 
-        assert_raises_rpc_error(-25, 'Inputs missing or spent', self.nodes[0].walletprocesspsbt, 'cHNidP8BAJoCAAAAAkvEW8NnDtdNtDpsmze+Ht2LH35IJcKv00jKAlUs21RrAwAAAAD/////S8Rbw2cO1020OmybN74e3Ysffkglwq/TSMoCVSzbVGsBAAAAAP7///8CwLYClQAAAAAWABSNJKzjaUb3uOxixsvh1GGE3fW7zQD5ApUAAAAAFgAUKNw0x8HRctAgmvoevm4u1SbN7XIAAAAAAAEAnQIAAAACczMa321tVHuN4GKWKRncycI22aX3uXgwSFUKM2orjRsBAAAAAP7///9zMxrfbW1Ue43gYpYpGdzJwjbZpfe5eDBIVQozaiuNGwAAAAAA/v///wIA+QKVAAAAABl2qRT9zXUVA8Ls5iVqynLHe5/vSe1XyYisQM0ClQAAAAAWABRmWQUcjSjghQ8/uH4Bn/zkakwLtAAAAAAAAQEfQM0ClQAAAAAWABRmWQUcjSjghQ8/uH4Bn/zkakwLtAAAAA==')
+        assert_raises_rpc_error(-22, "TX decode failed", self.nodes[0].walletprocesspsbt, "cHNidP8BAJoCAAAAAkvEW8NnDtdNtDpsmze+Ht2LH35IJcKv00jKAlUs21RrAwAAAAD/////S8Rbw2cO1020OmybN74e3Ysffkglwq/TSMoCVSzbVGsBAAAAAP7///8CwLYClQAAAAAWABSNJKzjaUb3uOxixsvh1GGE3fW7zQD5ApUAAAAAFgAUKNw0x8HRctAgmvoevm4u1SbN7XIAAAAAAAEAnQIAAAACczMa321tVHuN4GKWKRncycI22aX3uXgwSFUKM2orjRsBAAAAAP7///9zMxrfbW1Ue43gYpYpGdzJwjbZpfe5eDBIVQozaiuNGwAAAAAA/v///wIA+QKVAAAAABl2qRT9zXUVA8Ls5iVqynLHe5/vSe1XyYisQM0ClQAAAAAWABRmWQUcjSjghQ8/uH4Bn/zkakwLtAAAAAAAAQEfQM0ClQAAAAAWABRmWQUcjSjghQ8/uH4Bn/zkakwLtAAAAA==")
 
         self.log.info("Test that we can fund psbts with external inputs specified")