[aptos fuzz] add fuzzing target for u256 #18081
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zi0Black
reviewed
Nov 12, 2025
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| fuzz_target!(|data: &[u8]| { | ||
| if data.len() < 64 { | ||
| return; |
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To ensure it's correctly discarded by libFuzzer, return:
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zi0Black
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Nov 12, 2025
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| bytes.copy_from_slice(&data[0..32]); | ||
| let pri_u256_1 = PrimitiveU256::get_from_le_bytes(&bytes); | ||
| let eth_u256_1 = EthnumU256::get_from_le_bytes(&bytes); | ||
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| bytes.copy_from_slice(&data[32..64]); | ||
| let pri_u256_2 = PrimitiveU256::get_from_le_bytes(&bytes); | ||
| let eth_u256_2 = EthnumU256::get_from_le_bytes(&bytes); | ||
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| // Check conversion consistency | ||
| assert_eq!(pri_u256_1.turn_to_le_bytes(), eth_u256_1.turn_to_le_bytes()); | ||
| assert_eq!(pri_u256_2.turn_to_le_bytes(), eth_u256_2.turn_to_le_bytes()); | ||
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| // Check arithmetic operations | ||
| let add1 = PrimitiveU256::checked_add(pri_u256_1, pri_u256_2); | ||
| let add2 = EthnumU256::checked_add(eth_u256_1, eth_u256_2); | ||
| assert_eq!( | ||
| add1.map(|x| x.turn_to_le_bytes()), | ||
| add2.map(|x| x.turn_to_le_bytes()) | ||
| ); | ||
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| let sub1 = PrimitiveU256::checked_sub(pri_u256_1, pri_u256_2); | ||
| let sub2 = EthnumU256::checked_sub(eth_u256_1, eth_u256_2); | ||
| assert_eq!( | ||
| sub1.map(|x| x.turn_to_le_bytes()), | ||
| sub2.map(|x| x.turn_to_le_bytes()) | ||
| ); | ||
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| let mul1 = PrimitiveU256::checked_mul(pri_u256_1, pri_u256_2); | ||
| let mul2 = EthnumU256::checked_mul(eth_u256_1, eth_u256_2); | ||
| assert_eq!( | ||
| mul1.map(|x| x.turn_to_le_bytes()), | ||
| mul2.map(|x| x.turn_to_le_bytes()) | ||
| ); | ||
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Contributor
There was a problem hiding this comment.
Normally, it's suggested to split test cases/fuzzers as those are explored better stand-alone. But I guess the fuzzer is quite fast, and we can ignore it.
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Description
When introducing signed integers, we switched from
primitive-typestoethnumas the underneath crate to support ouru256type. This PR adds a harness to differentially fuzz the two crates on their operations that we reuse foru256.Running the harness can effectively cover the operations we care about. No disparity issues were found.
Type of Change
Which Components or Systems Does This Change Impact?
Note
Adds a fuzz target to differentially test
ethnum::U256againstprimitive_types::U256, with a comprehensive dictionary and dependency updates.u256_diff_fuzzintestsuite/fuzzer/fuzz/fuzz_targets/u256_diff_fuzz.rsto differentially testethnum::U256vsprimitive_types::U256across arithmetic, bitwise, shifts, and conversions.testsuite/fuzzer/fuzz/dictionaries/u256.dictcovering boundary cases for multiple bit-widths.ethnumand includeprimitive-typesin the fuzz crate.primitive-typesin rootCargo.tomlfrom0.10to0.12.2.Written by Cursor Bugbot for commit 5216de7. This will update automatically on new commits. Configure here.