New chain fork code crashes in block tests

[Gustav-Simonsson]

Looks like a off-by-one here: https://github.com/ethereum/go-ethereum/blob/develop/core/chain_manager.go#L575

> geth blocktest /home/gs/eth/tests/BlockTests/bcUncleTest.json 

   Welcome to the
      FRONTIER

----------------- Running Block Test "oneUncleGeneration2"
I0504 11:48:26.891498    5671 backend.go:193] Protocol Version: 60, Network Id: 0
I0504 11:48:26.891688    5671 backend.go:203] Blockchain DB Version: 2
I0504 11:48:26.893056    5671 chain_manager.go:235] Last block (#0) fd4af92a79c7fc2fd8bf0d342f2e832e1d4f485c85b9152d2039e03bc604fdca TD=0
I0504 11:48:26.893584    5671 ethash.go:94] Making cache for epoch: 0 (0) (0000000000000000000000000000000000000000000000000000000000000000)
I0504 11:48:28.048266    5671 ethash.go:99] Took: 1.154580887s
I0504 11:48:28.053199    5671 backend.go:403] Server started
I0504 11:48:28.053497    5671 ethash.go:94] Making cache for epoch: 0 (0) (0000000000000000000000000000000000000000000000000000000000000000)
I0504 11:48:29.201999    5671 ethash.go:99] Took: 1.148398724s
I0504 11:48:29.207903    5671 chain_manager.go:628] imported 1 block(s) (0 queued 0 ignored) in 5.692392ms. #1 [50471440 / 50471440]
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x4b5d0a]

goroutine 1 [running]:
github.com/ethereum/go-ethereum/core/types.(*Block).Hash(0x0, 0x0, 0x0, 0x0, 0x0)
    /home/gs/go/src/github.com/ethereum/go-ethereum/core/types/block.go:319 +0xca
github.com/ethereum/go-ethereum/core.(*ChainManager).InsertChain(0xc2080bd950, 0xc2080c7448, 0x1, 0x1, 0x0, 0x0, 0x0)
    /home/gs/go/src/github.com/ethereum/go-ethereum/core/chain_manager.go:575 +0x130b
github.com/ethereum/go-ethereum/tests.(*BlockTest).TryBlocksInsert(0xc2081b0640, 0xc2080bd950, 0x0, 0x0)
    /home/gs/go/src/github.com/ethereum/go-ethereum/tests/block_test_util.go:165 +0x2ef
main.runOneBlockTest(0xc2080821c0, 0xc2081b0640, 0xc2080c7748, 0x0, 0x0)
    /home/gs/go/src/github.com/ethereum/go-ethereum/cmd/geth/blocktest.go:112 +0x2fd
main.runBlockTest(0xc2080821c0)

[obscuren]

I just checked and it appears that the previous block can not be found using the GetBlockByNumber. Did you do anything differently for the tests?

[obscuren]

block:

I0504 12:28:01.121473   97305 chain_manager.go:631] imported 1 block(s) (0 queued 0 ignored) in 5.705345ms. #1 [50471440 / 50471440]
Block(#2): Size: 612.00 B TD: 262208 {
MinerHash: 27fbaba84d1a6a24e407af4755e736c5dd1b38781009fd29d73a25369a36381a
Header(faf46c175ab6e958dba9190557b36b072ccc76a6ccc76af6e09eb76418af9c80):
[
    ParentHash:     50471440735fab181157f681bec6f3c6143ece9da3567bb5a98751bd0d92d872
    UncleHash:      1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347
    Coinbase:       8888f1f195afa192cfee860698584c030f4c9db1
    Root:           a2a5e3d96e902272adb58e90c364f7b92684c539e0ded77356cf33d966f917fe
    TxSha           d0fa6c13f704258be01fef48588ccd57fcb0cff7ffe9d66d49f6abc33a4bfb65
    ReceiptSha:     5a750181d80a2b69fac54c1b2f7a37ebc4666ea5320e25db6603b90958686b27
    Bloom:          00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
    Difficulty:     131136
    Number:         2
    GasLimit:       3141592
    GasUsed:        21000
    Time:           1429521876
    Extra:
    MixDigest:          e6ef43d0623e75a53d4765853ced0dfb7732c21982da99968b742709acfb2753
    Nonce:          e0eb0c0afe18aa0f
]
Transactions:
[
    TX(a3691a54bfc425cceb22ba52917678d7ff94f221b859aebb59677b54e728e0ee)
    Contract: false
    From:     a94f5374fce5edbc8e2a8697c15331677e6ebf0b
    To:       095e7baea6a6c7c4c2dfeb977efac326af552d87
    Nonce:    1
    GasPrice: 1
    GasLimit  314159
    Value:    10
    Data:     0x
    V:        0x1c
    R:        0x1b6fed1b62694205e8a14aef67d0da4e508ca36f12f61def385a56d893564d48
    S:        0xbc085e190f0be43565356495433bea725be6a5148a246315e1614d9cd19ce99
    Hex:      f86001018304cb2f94095e7baea6a6c7c4c2dfeb977efac326af552d870a801ca01b6fed1b62694205e8a14aef67d0da4e508ca36f12f61def385a56d893564d48a00bc085e190f0be43565356495433bea725be6a5148a246315e1614d9cd19ce99
]
Uncles:
[]
}

self.getBlockByNumber(block.Number() - 1):

<nil>

self.GetBlock(block.ParentHash()):

Block(#1): Size: 612.00 B TD: 131072 {
MinerHash: 8e861bccc3c5b4f259b94c54ec588fb9e22fc93cb9b615416d47a1da204bd3d9
Header(50471440735fab181157f681bec6f3c6143ece9da3567bb5a98751bd0d92d872):
[
    ParentHash:     3ca4b1cb8594cc146df2d746536b670c09c4c2edb81298748b6b0c3c2ef83965
    UncleHash:      1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347
    Coinbase:       8888f1f195afa192cfee860698584c030f4c9db1
    Root:           2c15e8b5cb6cf880faa558c76c02a591e181ef2c4450ad92e53ae6c21093dc70
    TxSha           869af6e174056213a0039b95bb91ef272548985ae20487d746af666d02e2074c
    ReceiptSha:     e9244cf7503b79c03d3a099e07a80d2dbc77bb0b502d8a89d51ac0d68dd31313
    Bloom:          00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
    Difficulty:     131072
    Number:         1
    GasLimit:       3141592
    GasUsed:        21000
    Time:           1429521875
    Extra:
    MixDigest:          ba521732117b319c6b2edf47a5a1a933a246212d643700bb5ce838aa31f2fde0
    Nonce:          23914144df6d8b42
]
Transactions:
[
    TX(2f66c552d2f9014630b86c8d9f141a365ced7dffb95c3b9db6ef10448627f417)
    Contract: false
    From:     a94f5374fce5edbc8e2a8697c15331677e6ebf0b
    To:       095e7baea6a6c7c4c2dfeb977efac326af552d87
    Nonce:    0
    GasPrice: 1
    GasLimit  314159
    Value:    10
    Data:     0x
    V:        0x1b
    R:        0xd26e4915e9dd8af52ba47600da9660ebdc0c39911ebe9672418fc173fe0ad0fa
    S:        0x45aa2e72f5cce8bac030601844de212df77479e01abadf02f2ce107acc525735
    Hex:      f86080018304cb2f94095e7baea6a6c7c4c2dfeb977efac326af552d870a801ba0d26e4915e9dd8af52ba47600da9660ebdc0c39911ebe9672418fc173fe0ad0faa045aa2e72f5cce8bac030601844de212df77479e01abadf02f2ce107acc525735
]
Uncles:
[]
}

[Gustav-Simonsson]

Fix: #857

[obscuren]

Could you point me to fix in #857? I can only find a couple of name changes and comment moves.

[Gustav-Simonsson]

New PR which resolves the DoS vulnerability but still needs a proper fix for the underlying missing block number problem: #865