Project Zero Releases MAccConc — Tooling to Systematically Test Race Conditions in Kernel Code
What Happened — Google Project Zero published a new open‑source suite called MAccConc (Memory Access Concurrency). The tools automate exploration of all possible A‑B‑A interleavings for a given multi‑threaded test case, and provide both terminal‑ and GUI‑based interfaces for manual probing. The authors describe how the suite can be used to confirm manually discovered race‑condition bugs, create reliable regression tests, and support fuzzing‑driven discovery of concurrency defects in the Linux kernel. Source code and documentation are hosted on GitHub, with a demo that automatically exercises every interleaving of a sample test case.
Why It Matters for Trust & Control Assurance — Reliable detection of race‑condition bugs strengthens the secure development and testing control objective, giving organizations defensible evidence that concurrency risks are being actively managed.
Who Is Affected — Operating‑system vendors, cloud‑infrastructure providers, embedded‑device manufacturers, and any organization that builds or ships software with multi‑threaded components.
Recommended Actions
- Add MAccConc (or similar deterministic interleaving tools) to your CI/CD pipeline to generate repeatable concurrency test results.
- Capture test logs and interleaving diagrams as audit evidence for secure‑development controls.
- Map the new testing activity to your framework of record (e.g., NIST CSF 2.0 “Protect” function, ISO 27001 “A.14.2 Secure Development”).
Technical Notes
- The suite enumerates all A‑B‑A interleavings for a given test harness, eliminating nondeterministic timing reliance.
- It works on Linux kernel code; Windows/macOS support is limited to DTrace‑based delay injection.
- No CVE or active exploit is disclosed; the contribution is a developer‑oriented testing methodology.
Source: https://projectzero.google/2026/09/maccconc-race-condition.html