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Fix fuel configuration in fuzzers (#4440)

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Previously fuel configuration in our fuzzers ran afoul of #4439 so this
commit fixes how fuel is managed to avoid that issue.
This commit is contained in:
Alex Crichton
2022-07-13 11:02:06 -05:00
committed by GitHub
parent 18d9685eb3
commit 08a60a0f08
1 changed files with 16 additions and 13 deletions
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29
crates/fuzzing/src/oracles.rs
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@@ -124,13 +124,8 @@ pub fn instantiate(wasm: &[u8], known_valid: bool, config: &generators::Config,
let mut timeout_state = SignalOnDrop::default(); let mut timeout_state = SignalOnDrop::default();
match timeout { match timeout {
Timeout::Fuel(fuel) => { Timeout::Fuel(fuel) => set_fuel(&mut store, fuel),
// consume the default fuel in the store ...
let remaining = store.consume_fuel(0).unwrap();
store.consume_fuel(remaining - 1).unwrap();
// ... then add back in how much fuel we're allowing here
store.add_fuel(fuel).unwrap();
}
// If a timeout is requested then we spawn a helper thread to wait for // If a timeout is requested then we spawn a helper thread to wait for
// the requested time and then send us a signal to get interrupted. We // the requested time and then send us a signal to get interrupted. We
// also arrange for the thread's sleep to get interrupted if we return // also arrange for the thread's sleep to get interrupted if we return
@@ -553,12 +548,7 @@ pub fn table_ops(mut fuzz_config: generators::Config, ops: generators::table_ops
{ {
fuzz_config.wasmtime.consume_fuel = true; fuzz_config.wasmtime.consume_fuel = true;
let mut store = fuzz_config.to_store(); let mut store = fuzz_config.to_store();
set_fuel(&mut store, 1_000);
// consume the default fuel in the store ...
let remaining = store.consume_fuel(0).unwrap();
store.consume_fuel(remaining - 1).unwrap();
// ... then add back in how much fuel we're allowing here
store.add_fuel(1_000).unwrap();
let wasm = ops.to_wasm_binary(); let wasm = ops.to_wasm_binary();
log_wasm(&wasm); log_wasm(&wasm);
@@ -992,3 +982,16 @@ impl Drop for SignalOnDrop {
} }
} }
} }
fn set_fuel<T>(store: &mut Store<T>, fuel: u64) {
// Determine the amount of fuel already within the store, if any, and
// add/consume as appropriate to set the remaining amount to` fuel`.
let remaining = store.consume_fuel(0).unwrap();
if fuel > remaining {
store.add_fuel(fuel - remaining).unwrap();
} else {
store.consume_fuel(remaining - fuel).unwrap();
}
// double-check that the store has the expected amount of fuel remaining
assert_eq!(store.consume_fuel(0).unwrap(), fuel);
}