Achieving Zero-Bug Embedded Software: Steps for Error-Free Code

This is a guest post by RunSafe Security.

RunSafe Security secures embedded software in critical infrastructure by eliminating memory-based risks, automating SBOMs and remediation, and monitoring deployed systems for built-in resilience from build to runtime.

The Crowdstrike Falcon outage is an event most people—and developers—aren’t going to forget for some time, and it’s an excellent example of why striving for bug-free software is so important for reliability and safety. Of course, software testing is much easier said than done, and many tools available today miss critical issues in code, like memory safety vulnerabilities, which are widespread across embedded devices. Despite the challenges, there are steps to take to reduce the risk of buggy software and the issues that come along with it.

Why Bug-Free Embedded Software Matters

Errors in code lead to safety, security, and financial issues. A single software bug or error can cause system crashes, remote code execution, data theft, or other critical failures in embedded systems across automotive, aviation, industrial automation, and other critical infrastructure. In the case of Crowdstrike, a memory access violation bug likely caused the crash.

In addition, bugs found later in the software development lifecycle are much more costly than those found during coding and testing and addressed early on. Once software is released, the cost of a bug can rise to $64,000 or more. Achieving zero bugs can save resources by reducing time spent on debugging, emergency patches, recalls, customer support costs, and more.

Another important consideration in a world that runs on software is safety. A bug in software can lead to physical harm. Regulatory and certification requirements, like ISO 26262 for automotive and DO-178C in aviation, make bug-free software imperative to achieve safety standards.

Common Bugs in Embedded Software

Embedded systems are prone to a range of bugs, including memory safety issues, concurrency defects, undefined behaviors, and integration challenges. These bugs can be subtle, difficult to detect, and have severe consequences in safety- or mission-critical applications.

Memory safety issues: Memory safety vulnerabilities are one of the biggest security risks in C and C++ applications, with studies showing they account for around 70% of high-severity vulnerabilities. These critical security flaws include buffer overflows, use-after-free bugs, or accesses to uninitialized memory.

Concurrency Problems: Concurrency problems are a major challenge in multi-threaded and parallel programming environments. Deadlock and race conditions are two examples of concurrency problems that can lead to incorrect behavior.

Undefined Behaviors: C/C++ standards leave certain behaviors undefined, such as division by zero or writing outside a memory buffer, which can lead to critical errors like program crashes or vulnerabilities such as buffer overflows. Undefined behavior occurs when code violates the language's rules, resulting in unpredictable outcomes.

Integration Bugs: Many modern embedded systems combine languages, like C/C++ with Rust, for safety or performance. However, this can reintroduce memory safety issues and undefined behaviors into code.

4 Steps to Achieving Zero Bugs in Embedded Software

1. Implement Advanced Testing Techniques

Sanitizers, memory debugging tools, fuzzers, and static analyzers are all great tools for examining code. However, these techniques cannot guarantee the absence of errors and often miss certain classes of bugs. By some counts, static analyzers for C/C++ miss 47%–80% of real vulnerabilities.

That’s a major gap that advanced tools are using formal methods to address. Formal methods are a mathematically rigorous approach to verifying software correctness. For example, tools like the TrustInSoft Analyzer provide formal proofs of software correctness to eliminate undefined behaviors in mature, current, and future C and C++ code to ensure that no memory-related vulnerabilities go unnoticed.

2. Deploy Runtime Exploit Prevention

While code testing is essential, there’s always a chance for bugs to slip through into production. Runtime exploit prevention is a security solution that protects embedded software by eliminating the ability for attackers to exploit both known and unknown memory safety vulnerabilities in code.

One example is Load-Time Function Randomization (LFR), an advanced technique that randomizes individual functions within a program every time the software loads to create a unique memory layout. Because the functions are randomized, attackers cannot find a path to execute their attack. 

As a result, LFR prevents memory corruption exploits, like buffer overflows and use-after-free errors, without requiring code rewrites into memory safe languages and before patches are available. For example, RunSafe Security’s Protect solution deploys LFR to defend embedded systems across critical infrastructure.

3. Shift to Safer Programming Practices

Following secure coding practices is the foundation for bug-free code. When possible, this includes using memory safe languages, like Rust, for new projects or high-criticality applications that can be rewritten. In cases where that’s not possible, applying runtime protections is becoming best practice. TrustInSoft offers audit services for Rust/C/C++ integration to ensure safety when maintaining legacy code.

4. Integrate Security Early in Development

Incorporating safety checks during the build process is crucial for creating secure and reliable software. Tools like TrustInSoft help reduce in-the-field fixes and minimize the overall attack surface that adversaries can exploit by using advanced static analysis for early vulnerability detection, even with hardware awareness capabilities. For code that isn’t formally verified, solutions like RunSafeProtect provide an additional layer of security by protecting code at both build and runtime. RunSafe’s approach ensures enhanced security without impacting performance or requiring code rewrites, making it an effective solution for modern software development.

Building Reliable and Secure Software

Achieving near-zero bugs in embedded software is crucial for ensuring safety, security, and efficiency in modern systems. To accomplish this, developers can leverage advanced code analysis tools and runtime protections, particularly when working with languages like C/C++ and Rust. These tools help identify vulnerabilities early and safeguard applications, making them more reliable and secure.