Broken argument positions cause method to repeat almost infinitely

[snail-fuji]

Hello, guys! I've got a problem with input decoding, can you help me with it?

from ethereum.abi import decode_abi
from ethereum.utils import decode_hex    
arg_types = ['address[4][]', 'uint256[6][]', 'uint8[1][]', 'bool[]', 'uint8[]', 'bytes32[]', 'bytes32[]', 'address', 'uint16']
call_data = "0xe78aadb20000000000000000000000000000000000000000000000000000000000000120000000000000000000000000000000000000000000000000000000000000024000000000000000000000000000000000000000000000000000000000000003e0000000000000000000000000000000000000000000000000000000000000044000000000000000000000000000000000000000000000000000000000000004a0000000000000000000000000000000000000000000000000000000000000054000000000000000000000000000000000000000000000000000000000000005a0000000000000000000000000b94065482ad64d4c2b9252358d746b39e820a5820000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000200000000000000000000000087c6117ef0935b1df3f9d93d9b39516eb8141870000000000000000000000000ef68e7c694f40c8202821edf525de3782458639f000000000000000000000000b94065482ad64d4c2b9252358d746b39e820a58200000000000000000000000057c3153be7cee64da0244da98902a6a0fbd6f5d30000000000000000000000008c82798e7e491e9bf6e6e28e2bc31f781d1175a2000000000000000000000000c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2000000000000000000000000b94065482ad64d4c2b9252358d746b39e820a5820000000000000000000000006e79fe67d43095e6b95f00beeaa4a89a3db6385200000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000001bc16d674ec8000000000000000000000000000000000000000000000000000000071afd498d0000000000000000000000000000000000000000000000000000000000005afeace4000000000000000000000000000000000000000000000000000000005afebaf400000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001bc16d674ec8000000000000000000000000000000000000000000000000000000071afd498d00000000000000000000000000000000000000000000000000001bc16d674ec80000000000000000000000000000000000000000000000000000000000005afead23000000000000000000000000000000000000000000000000000000005afebb33000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000071afd498d00000000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000001b000000000000000000000000000000000000000000000000000000000000001c000000000000000000000000000000000000000000000000000000000000001b000000000000000000000000000000000000000000000000000000000000001b00000000000000000000000000000000000000000000000000000000000000046447466b00ad173ecad372d3711943e0a2677af6a3baa7012e8b88864bd47818669ba4472872c03574a240ec7b5527298c52cc2ff75cdeb9e2c157ca0f6eff1d09e9e13fd62097527e71280de3e8c091d7f7b788e21a19118f8c397c94f756d4701f9a3805f5ccdda2449ac0a798089cd4bac15622b6ba7227785ddb0afbb9cd000000000000000000000000000000000000000000000000000000000000000419380a2a3e0ad8a6073c2d36b40d4a469a1111cc6f83fab69293f70559821da655a3443ab90d9233670f4aff0ab12519364056ca6ab0323c9f9d0188b3b37a7e4e02281ddc6a197e149c4c1684cae2fb6536fb319b6ded4ee1574d33b5836d36252d5633c682288c913e7e44a2ff729df463cfb1f4fb0334e8b6270778ce9093"
call_data_bin = decode_hex(call_data)
inputs = decode_abi(arg_types, call_data_bin[4:])

So, this code stucks for a long time.
I use pyethereum 2.3.1, python3 and ubuntu 16.04

Thanks in advance!

[snail-fuji]

Seems like argument positions in transaction are invalid, and the second bytes32[] array tries to interpret wrong byte sequence as length:

• Argument position says that the argument data starts from 1440
  ...
  [5]: 0000000000000000000000000000000000000000000000000000000000000540
  [6]: 00000000000000000000000000000000000000000000000000000000000005a0
  [7]: 000000000000000000000000b94065482ad64d4c2b9252358d746b39e820a582
  ...

• Value in the first 32 bytes for this position says: "WTF is going on?!?!"
  ...
  [41]: 000000000000000000000000000000000000000000000000000000000000001b
  [42]: 0000000000000000000000000000000000000000000000000000000000000004
  [43]: 6447466b00ad173ecad372d3711943e0a2677af6a3baa7012e8b88864bd47818
  [44]: 669ba4472872c03574a240ec7b5527298c52cc2ff75cdeb9e2c157ca0f6eff1d
  Length is read from this position
  [45]: 09e9e13fd62097527e71280de3e8c091d7f7b788e21a19118f8c397c94f756d4
  [46]: 701f9a3805f5ccdda2449ac0a798089cd4bac15622b6ba7227785ddb0afbb9cd
  But it stored there
  [47]: 0000000000000000000000000000000000000000000000000000000000000004
  [48]: 19380a2a3e0ad8a6073c2d36b40d4a469a1111cc6f83fab69293f70559821da6
  ...
  Maybe, it'll be helpful to add a timeout or an assertion (i.e. assert length <= positions_difference) to prevent such cases.

The original transaction can be found here: https://etherscan.io/tx/0x9f053648f7e6a6e6a89ce3f5524dab3c21a2368aa16c69dce0182395c5a54831

And it's not alone in ethereum blockchain :( There are plenty of transactions with broken argument positions. Maybe, I missed something in a standard?