Race Condition Affecting rcu_cell package, versions <0.1.10
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-RUST-RCUCELL-1316266
- published7 Jul 2021
- disclosed14 Nov 2020
- creditsslab-gatech
Introduced: 14 Nov 2020
CVE-2020-36451 (opens in a new tab)How to fix?
Upgrade rcu_cell to version 0.1.10 or higher.
Overview
rcu_cell is an a lockless rcu cell implementation.
Affected versions of this package are vulnerable to Race Condition. It unconditionally implements Send/Sync for RcuCell<T>. This allows users to send T: !Send to other threads (while T enclosed within RcuCell<T>), and allows users to concurrently access T: !Sync by using the APIs of RcuCell<T> that provide access to &T. This can result in memory corruption caused by data races.
PoC
# Run the below program in debug mode use rcu_cell::RcuCell;use std::rc::Rc; use std::sync::Arc; use std::thread;
fn main() { //
Rcis neitherSendnorSynclet rcu_cell = RcuCell::new(Some(Rc::new(0_i32))); let arc_parent = Arc::new(rcu_cell);let mut child_threads = vec![]; for _ in 0..5 { let arc_child = Arc::clone(&arc_parent); child_threads.push(thread::spawn(move || { for _ in 0..1000 { let reader = arc_child.as_ref().read(); // data race on internal `strong_count` of `Rc` let _ = Rc::clone(&reader.unwrap()); } })); } for child in child_threads { child.join().expect("failed to join child thread"); } assert_eq!(Rc::strong_count(arc_parent.read().as_ref().unwrap()), 1);
}