evm: fix modexp edge cases #3169
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Have added a fuzzer which I will run now. It finds more error cases. |
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Fuzzer tests: run inputs [0,1,2] on the modExp inputs (6 fields: |
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Test cases: array of |
acolytec3
reviewed
Nov 28, 2023
| @@ -151,17 +151,10 @@ export function precompile05(opts: PrecompileInput): ExecResult { | |||
| return OOGResult(opts.gasLimit) | |||
| } | |||
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| if (bLen === BIGINT_0) { | |||
| if (bLen === BIGINT_0 && mLen === BigInt(0)) { | |||
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| if (bLen === BIGINT_0 && mLen === BigInt(0)) { | |
| if (bLen === BIGINT_0 && mLen === BIGINT_0) { |
acolytec3
reviewed
Nov 28, 2023
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Closes #3168
This PR fixes the edge cases in ModExp. Specifically, ModExp has 6 inputs, and the inputs for [0,1,2] are all tested on all inputs. These are cross-referenced against infura. (File here: 144963a)
Test files are here. The format is [input, expectedOutput]
tests.txt
Note: one of the causes is that
bigIntToBytes(BigInt(0))returnsUint8Array(1) [ 0 ](length 1) instead ofUint8Array(0) [](length 0). If you thensetLengthLeft(r, 0)then it still outputs the array with length 1. This raises 2 questions:bigIntToBytesonBigInt(0)return the empty array? (Note: this is super breaking so we cannot do it, we could introduce a new method?)setLengthLeftthrow if the expected length is lower than the current length? (It is unknown if we should trim left or right 🤔 )