core/vm: fix a corner case in EIP-7823 #16494
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chfast
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chfast
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In evmone, I handle EIP-7823 in the "gas" function by returning the MAX_GAS in case the lengths are above the limits. May this potentially improve code structure?
To my mind relying on the gas function is a bit brittle because it disperses EIP-7823 checks among two functions. |
I think this would keep the EIP-7823 in the gas function only. But I'm not pushing here. |
| // 32 - 8 bytes are truncated in the Uint64 conversion above | ||
| baseLenHighBitsAreZero = allZero(header[0 : 32-8]) | ||
| expLenHighBitsAreZero = allZero(header[32 : 64-8]) | ||
| modLenHighBitsAreZero = allZero(header[64 : 96-8]) |
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I think baseLenHighBitsAreZero and modLenHighBitsAreZero are always true in practice because otherwise we would get huge gas cost because of the "mult complexity" calculation. I.e. these will not be testable.
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Yes, but I'd like to have them here for consistency and robustness so that Run is self-explanatory w/o a hidden dependency on the behaviour of RequiredGas.
core/vm/contracts.go
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| // Handle a special case when both the base and mod length is zero | ||
| if baseLen == 0 && modLen == 0 && baseLenHighBitsAreZero && modLenHighBitsAreZero { |
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I think the original check was overspecified. This is true for only the modLen being 0 (you can skip the base check).
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You're right. I've amended the special case.
Make sure that lengths of the form 2^64*_n_, _n_>=1 are not accepted (that would be a violation of [EIP-7823](https://eips.ethereum.org/EIPS/eip-7823)). N.B. EIP-7823 restricts the range of `expLen` even in the special case `baseLen == 0 && modLen == 0`.
Make sure that lengths of the form 2^64*_n_, _n_>=1 are not accepted (that would be a violation of [EIP-7823](https://eips.ethereum.org/EIPS/eip-7823)). N.B. EIP-7823 restricts the range of `expLen` even in the special case `baseLen == 0 && modLen == 0`.
Make sure that lengths of the form 2^64*n, n>=1 are not accepted (that would be a violation of EIP-7823).
N.B. EIP-7823 restricts the range of
expLeneven in the special casebaseLen == 0 && modLen == 0.