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add cooloff period for rapidly exiting libFuzzer targets (#1002)
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bmc-msft authored Jun 18, 2021
1 parent 888c045 commit c8862c7
Showing 1 changed file with 13 additions and 2 deletions.
15 changes: 13 additions & 2 deletions src/agent/onefuzz-agent/src/tasks/fuzz/libfuzzer_fuzz.rs
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ use tokio::{
select,
sync::{mpsc, Notify},
task,
time::{sleep, Duration},
time::{sleep, Duration, Instant},
};
use uuid::Uuid;

Expand All @@ -37,6 +37,9 @@ const PROC_INFO_PERIOD: Duration = Duration::from_secs(30);
// Period of reporting fuzzer-generated runtime stats.
const RUNTIME_STATS_PERIOD: Duration = Duration::from_secs(60);

// Period for minimum duration between launches of libFuzzer
const COOLOFF_PERIOD: Duration = Duration::from_secs(10);

/// Maximum number of log message to safe in case of libFuzzer failing,
/// arbitrarily chosen
const LOGS_BUFFER_SIZE: usize = 1024;
Expand Down Expand Up @@ -160,6 +163,7 @@ impl LibFuzzerFuzzTask {
) -> Result<()> {
let local_input_dir = self.create_local_temp_dir().await?;
loop {
let instant = Instant::now();
self.run_fuzzer(&local_input_dir.path(), worker_id, stats_sender)
.await?;

Expand All @@ -181,6 +185,13 @@ impl LibFuzzerFuzzTask {
)
})?;
}

// if libFuzzer is exiting rapidly, give some breathing room to allow the
// handles to be reaped.
let runtime = instant.elapsed();
if runtime < COOLOFF_PERIOD {
sleep(COOLOFF_PERIOD - runtime).await;
}
}
}

Expand Down Expand Up @@ -335,7 +346,7 @@ async fn report_fuzzer_sys_info(
) -> Result<()> {
// Allow for sampling CPU usage.
let mut period = tokio::time::interval_at(
tokio::time::Instant::now() + PROC_INFO_COLLECTION_DELAY,
Instant::now() + PROC_INFO_COLLECTION_DELAY,
PROC_INFO_PERIOD,
);
loop {
Expand Down

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