Memory-safety bugs are a major source of vulnerabilities in C code. Much work has focused on spatial memory safety (e.g., buffer overflows), while temporal memory safety (e.g., use-after-free) has received less attention. One solution for achieving temporal memory safety is to apply an ownership model to an existing program and enforce it. In this paper, we describe the design and implementation of a new temporal memory safety model for C source code. Our design improves on CERT's Pointer Ownership Model with enhancements including use of a SAT solver to enforce constraint satisfaction, LLMs to complete a per-program model, and an improved mechanism to prevent use-after-free errors inspired by Rust's borrow checker and object lifetimes. Our implementation performed well on a large test suite of memory-safe and memory-unsafe code examples. We tested all 4,604 C code examples for the 5 CWEs associated with temporal memory safety (CWEs 401, 415, 416, 590, 761) from the Juliet C/C++ test suite. In our tests, all of the memory-unsafe examples were correctly recognized as unsafe, and 81% of the 2,302 memory-safe examples were correctly recognized as memory-safe.

Colluding apps, or a combination of a malicious app and leaky app, can use intents (messages sent to Android app components) to exfiltrate sensitive or private information from an Android phone. This paper describes a novel static analysis method "Precise-DF" to detect taint flow in Android app sets (including flows involving multiple apps) that is precise, fast, and uses relatively little disk and memory space. Precise-DF re-uses the fast modular analysis of the DidFail static analysis tool, and adds context and therefore precision with parameterized summaries of potential data flows. We added Boolean formulas to DidFail's flow equations, to record conditions of control flow paths relevant to possible taint flows. The method that we have refined (a modular analysis with parameterized summaries of flow of sensitive information) is generally applicable to the class of problems involving taint flow analysis for software systems that communicate by message passing. This paper also describes how an enterprise architecture could use Precise-DF to analyze and enforce compliance with dataflow policies.