Context-sensitive pointer analysis tends to generate excessive spurious points-to relations, causing inefficiency and imprecision. We introduce stack filtering, a novel approach using Rust's stack object lifetime information to address this issue. It identifies and eliminates context-sensitive points-to relations involving variables pointing to inactive stack objects beyond their lifetimes. Stack filtering is a lightweight two-phase process. It first assesses stack object liveness based on function reachability, leveraging an efficient call graph generated by Rapid Type Analysis (RTA). Then, this filtering is applied during the main pointer analysis.

Context-free language (CFL) reachability is a critical framework for various program analyses, widely adopted despite its computational challenges due to cubic or near-cubic time complexity. This often leads to significant performance degradation in client applications. Notably, in real-world scenarios, clients typically require reachability information only for specific source-to-sink pairs, offering opportunities for targeted optimization. We introduce MoYe, an effective regularization-based graph simplification technique designed to enhance the performance of client-driven CFL-reachability analyses by pruning non-contributing edges—those that do not participate in any specified CFL-reachable paths. MoYe employs a regular approximation to ensure exact reachability results for all designated node pairs and operates linearly with respect to the number of edges in the graph. This lightweight efficiency makes MoYe a valuable pre-processing step that substantially reduces both computational time and memory requirements for CFL-reachability analysis, outperforming a recent leading graph simplification approach. Our evaluations with two prominent CFL-reachability client applications demonstrate that MoYe can substantially improve performance and reduce resource consumption.

Existing program analysis tools for Rust lack the ability to effectively detect security vulnerabilities due to the absence of an accurate call graph and precise points-to information. We present Rupta, the first context-sensitive pointer analysis framework designed for Rust, with a particular focus on its role in constructing call graphs. Operating on Rust MIR, Rupta employs callsite-based context-sensitivity and on-the-fly call graph construction to address a range of pointer analysis challenges, including method/function calls, pointer casts, and nested structs, while preserving type information.

Abstract Since its inception two decades ago, Soot has become one of the most widely used open-source static analysis frameworks. Over time it has been extended with the contributions of countless researchers. Yet, at the same time, the requirements for Soot have changed over the years and become increasingly at odds with some of the major design decisions that underlie it. In this work, we thus present SootUp, a complete reimplementation of Soot that seeks to fulfill these requirements with a novel design, while at the same time keeping elements that Soot users have grown accustomed to.

The IFDS algorithm can be both memory- and compute-intensive for large programs as it needs to store a huge amount of path edges in memory and process them until a fixed point. In general, an IFDS-based data-flow analysis, such as taint analysis, aims to discover only the data-flow facts at some program points. Maintaining a huge amount of path edges (with many visited only once) wastes memory resources, and consequently, reduces its scalability and efficiency (due to frequent re-hashings for the path-edge data structure used).

The IFDS-based taint analysis employs two mutually iterative passes: a forward pass that identifies taints and a backward pass that detects aliases. This approach ensures both flow and context sensitivity, leading to remarkable precision. To preserve flow sensitivity, the IFDS-based taint analysis enhances data abstractions with activation statements that pinpoint the moment they acquire taint. Nonetheless, this mechanism can inadvertently introduce equivalent, yet redundant, value flows. This occurs when distinct activation statements are linked with the same data abstraction, resulting in unnecessary computational and memory-intensive demands on the analysis process. We introduce MergeDroid, a novel approach to improve the efficiency of IFDS-based taint analysis by consolidating equivalent value flows. This involves merging activation statements linked to the same data abstraction from various reachable data facts that are reachable at a given program point during the backward pass. This process generates a representative symbolic activation statement applicable to all equivalent data facts, reducing them to a single symbolic data fact. During the forward pass, when this symbolic data fact returns to its point of creation, the analysis reverts to the original data facts alongside their initial activation statements. This merge-and-replay strategy eliminates redundant value flow propagation, resulting in performance gains. Furthermore, we also improve analysis efficiency and precision by leveraging context-sensitive insights from activation statements. Our evaluation on 40 Android apps demonstrates that MergeDroid significantly enhances IFDS-based taint analysis performance. On average, MergeDroid accelerates analysis by 9.0× while effectively handling 6 more apps scalably. Additionally, it reduces false positives by significantly decreasing reported leak warnings, achieving an average reduction of 19.2%.

The extensive use of libraries in modern software impedes the scalability of pointer analysis. To address this issue, library summarization can be beneficial, but only if the resulting summary-based pointer analysis is faster without sacrificing much precision in the application code. However, currently, no library summarization approaches exist that meet this design objective. This paper presents a novel approach that solves this problem by using k-object-sensitive pointer analysis, k-obj, for Java. The approach involves applying k-obj, along with a set of summary-based inference rules, to generate a k-object-sensitive library summary. By replacing the program's library with this summary and applying k-obj, the efficiency of the program can be significantly improved while maintaining nearly the same or better precision in the application code. We validate our approach with an implementation in Soot and an evaluation using representative Java programs.

In this paper, we introduce DebloaterX, a new approach for automatically identifying context-independent objects to debloat contexts in object-sensitive pointer analysis ( k obj). Object sensitivity achieves high precision, but its context construction mechanism combines objects with their contexts indiscriminately. This leads to a combinatorial explosion of contexts in large programs, resulting in inefficiency. Previous research has proposed a context-debloating approach that inhibits a pre-selected set of context-independent objects from forming new contexts, improving the efficiency of k obj. However, this earlier context-debloating approach under-approximates the set of context-independent objects identified, limiting performance speedups. We introduce a novel context-debloating pre-analysis approach that identifies objects as context-dependent only when they are potentially precision-critical to k obj based on three general container-usage patterns. Our research finds that objects containing no fields of ”abstract” (i.e., open) types can be analyzed context-insensitively with negligible precision loss in real-world applications. We provide clear rules and efficient algorithms to recognize these patterns, selecting more context-independent objects for better debloating. We have implemented DebloaterX in the Qilin framework and will release it as an open-source tool. Our experimental results on 12 standard Java benchmarks and real-world programs show that DebloaterX selects 92.4% of objects to be context-independent on average, enabling k obj to run significantly faster (an average of 19.3x when k = 2 and 150.2x when k = 3) and scale up to 8 more programs when k = 3, with only a negligible loss of precision (less than 0.2%). Compared to state-of-the-art alternative pre-analyses in accelerating k obj, DebloaterX outperforms Zipper significantly in both precision and efficiency and outperforms Conch (the earlier context-debloating approach) in efficiency substantially while achieving nearly the same precision.

Object-sensitive pointer analysis, which separates the calling contexts of a method by its receiver objects, is known to achieve highly useful precision for object-oriented languages such as Java. Despite recent advances, all object-sensitive pointer analysis algorithms still suffer from the scalability problem due to the combinatorial explosion of contexts in large programs. In this article, we introduce a new approach, Conch , that can be applied to debloat contexts for all object-sensitive pointer analysis algorithms, thereby improving significantly their efficiency while incurring a negligible loss of precision. Our key insight is to approximate a recently proposed set of two necessary conditions for an object in a program to be context-sensitive, i.e., context-dependent (whose precise verification is undecidable) with a set of three linearly verifiable conditions in terms of the number of edges in the pointer assignment graph (PAG) representation of the program. These three linearly verifiable conditions, which turn out to be almost always necessary in practice, are synthesized from three key observations regarding context-dependability for the objects created and used in real-world object-oriented programs. To develop a practical implementation for Conch , we introduce an IFDS-based algorithm for reasoning about object reachability in the PAG of a program, which runs linearly in terms of the number of edges in the PAG. By debloating contexts for three representative object-sensitive pointer analysis algorithms, which are applied to a set of representative Java programs, Conch can speed up these three baseline algorithms substantially at only a negligible loss of precision (less than 0.1%) with respect to several commonly used precision metrics. In addition, Conch also improves their scalability by enabling them to analyze substantially more programs to completion than before (under a time budget of 12 hours). Conch has been open-sourced (http://www.cse.unsw.edu.au/~corg/tools/conch), opening up new opportunities for other researchers and practitioners to further improve this research. To demonstrate this, we introduce one extension of Conch to accelerate further the three baselines without losing any precision, providing further insights on extending Conch to make precision-efficiency tradeoffs in future research.

Object-sensitive pointer analysis (denotedkobjunder$k$-limiting) for an object-oriented program can be accelerated if context-sensitivity can be selectively applied to only some precision-critical variables/objects in a program. Existing pre-analyses for making such selections, which are performed as whole-program analyses to a program, are developed based on two broad approaches. One approach preserves the precision of object-sensitive pointer analysis but achieves limited speedups by reasoning about all the possible value flows in the program conservatively, while the other approach achieves greater speedups but sacrifices precision (often unduly) by examining only some but not all the value flows in the program heuristically. In this paper, we introduce a new pre-analysis approach,Turner$^{\mathcal{m}}$(where$\mathcal {m}$stands for modularity), that represents a sweet spot between these two existing ones, as it is designed to enablekobjto run significantly faster than the former approach and achieve significantly better precision than the latter approach.Turner$^{\mathcal{m}}$is simple, lightweight yet effective due to two novel aspects in its design. First, we exploit a key observation that some precision-uncritical objects in the program can be approximated based on the object-containment relationship pre-established (from Andersen's analysis). In practice, this approximation introduces only a small degree of imprecision intokobj. Second, leveraging this initial approximation, we apply a novel object reachability analysis to the program by pre-analyzing its methods according to a reverse topological order of its call graph. When pre-analyzing each method, we make use of a simple DFA (Deterministic Finite Automaton) to reason about object reachability intra-procedurally from its entry to its exit along all the possible value flows established by its statements to identify its precision-critical variables/objects. In practice, this new modular object reachability analysis, which runs linearly in terms of the number of statements in the program, introduces again only a small loss of precision intokobj. We have validatedTurner$^{\mathcal{m}}$with an open-source implementation inSoot(already publicly available) against the state of the art by using a set of 12 widely used Java benchmarks and applications.

Object-sensitive pointer analysis for an object-oriented program can be accelerated if context-sensitivity can be selectively applied to some precision-critical variables/objects in the program. Existing pre-analyses, which are performed to make such selections, either preserve precision but achieve limited speedups by reasoning about all the possible value flows in the program conservatively or achieve greater speedups but sacrifice precision (often unduly) by examining only some but not all the value flows in the program heuristically. In this paper, we introduce a new approach, named Turner, that represents a sweet spot between the two existing ones, as it is designed to enable object-sensitive pointer analysis to run significantly faster than the former approach and achieve significantly better precision than the latter approach. Turner is simple, lightweight yet effective due to two novel aspects in its design. First, we exploit a key observation that some precision-uncritical objects can be approximated based on the object-containment relationship pre-established (by applying Andersen’s analysis). This approximation introduces a small degree yet the only source of imprecision into Turner. Second, leveraging this initial approximation, we introduce a simple DFA to reason about object reachability for a method intra-procedurally from its entry to its exit along all the possible value flows established by its statements to finalize its precision-critical variables/objects identified. We have validated Turner with an implementation in Soot against the state of the art using a set of 12 popular Java benchmarks and applications.

We Introduce a new approach, Conch, for debloating contexts for all the object-sensitive pointer analysis algorithms developed for object-oriented languages, where the calling contexts of a method are distinguished by its receiver objects. Our key insight is to approximate a recently proposed set of two necessary conditions for an object to be context-sensitive, i.e., context-dependent (whose precise verification is undecidable) with a set of three linearly verifiable conditions (in terms of the number of statements in the program) that are almost always necessary for real-world object-oriented applications, based on three key observations regarding context-dependability for their objects used. To create a practical implementation, we introduce a new IFDS-based algorithm for reasoning about object reachability in a program. By debloating contexts for two representative object-sensitive pointer analyses applied to a set of 12 representative Java programs, Conch can speed up the two baselines together substantially (3.1x on average with a maximum of 15.9x) and analyze 7 more programs scalably, but at only a negligible loss of precision (less than 0.1%).

Object sensitivity is widely used as a context abstraction for computing the points-to information context-sensitively for object-oriented programming languages such as Java. Due to the combinatorial explosion of contexts in large object-oriented programs, k -object-sensitive pointer analysis (under k -limiting), denoted k -obj , is often inefficient even when it is scalable for small values of k , where k ⩽ 2 holds typically. A recent popular approach for accelerating k -obj trades precision for efficiency by instructing k -obj to analyze only some methods in a program context-sensitively, determined heuristically by a pre-analysis. In this article, we investigate how to develop a fundamentally different approach, Eagle , for designing a pre-analysis that can make k -obj run significantly faster while maintaining its precision. The novelty of Eagle is to enable k -obj to analyze a method with partial context sensitivity (i.e., context-sensitively for only some of its selected variables/allocation sites) by solving a context-free-language (CFL) reachability problem based on a new CFL-reachability formulation of k -obj . By regularizing one CFL for specifying field accesses and using another CFL for specifying method calls, we have formulated Eagle as a fully context-sensitive taint analysis (without k -limiting) that is both effective (by selecting the variables/allocation sites to be analyzed by k -obj context-insensitively so as to reduce the number of context-sensitive facts inferred by k -obj in the program) and efficient (by running linearly in terms of the number of pointer assignment edges in the program). As Eagle represents the first precision-preserving pre-analysis, our evaluation focuses on demonstrating its significant performance benefits in accelerating k -obj for a set of popular Java benchmarks and applications, with call graph construction, may-fail-casting, and polymorphic call detection as three important client analyses.

The Android framework provides sensitive APIs for Android apps to access the user's private information, e.g., SMS, call logs and locations. Whether a sensitive API call in an app is legitimate or not depends on whether the app has provided enough natural-language semantics to reflect the need for the permission. The prior efforts on analyzing description-to-permission fidelity in an app are all static. Some check whether the permissions requested (or sensitive APIs used) by the app are consistent with the functionalities described by the app. These app-level techniques are too coarse-grained, as they cannot tell if a sensitive API call under a certain runtime context, such as a UI state, is legitimate or not. Others attempt to establish this connection by performing a data-flow analysis, but such fine-grained API-level static analyses are too imprecise to handle a variety of dynamic language features used in Android apps, including dynamic class loading, reflection and code obfuscation. We introduce APICOG, an automated fine-grained API-level approach, representing the first dynamic description-to-permission fidelity analysis for an Android app that can check if a sensitive API call is legitimate or not under a given runtime context. APICOGrelates each sensitive API call with a UI state, called its UI context, under which the call is made via dynamic analysis and then extracts the text-based semantics for each UI context from its associated text- and image-typed attributes by applying a natural language processing (NLP) technique. Finally, APICOGrelies on machine-learning to deduce if a sensitive API call under a UI context is legitimate or not. We have evaluated APICOGwith thousands of Android apps drawn from a third-party market and a malware dataset, achieving an accuracy of 97.7%, a precision of 94.1% and a recall of 92.8% overall, outperforming the prior art in all the three metrics.

Android supports an event dispatching system that reacts to system and user actions by generating events. However, lack of synchronization between events can lead to event-based races in Android apps. Such event-based races are difficult to detect dynamically due to the challenges faced in generating the right events to satisfy the right event-dependent conditional branches, so that their guarded racy statements can be reached. As a result, existing dynamic tools, which try to find and reschedule some race-triggering events heuristically, are often ineffective.We introduce SIEVE, a tool for exposing event-based races in Android apps dynamically by leveraging a new selective branch instrumentation technique. For the conditionals potentially affecting a race (detected, say, by a static tool), SIEVE fixes the true/false outcomes of some of these conditionals based on a systematic branch analysis, which analyzes the satisfiability of all the conditionals guarding the given racy statements and their safeness for instrumentation. By instrumenting certain branches selectively this way, we can not only expose effectively event-based races but also reduce substantially the negative ramifications of instrumentation (e.g., reporting non-existent races and introducing unexpected crashes during dynamic execution). An evaluation of SIEVE with 25 Android apps shows that our tool can expose event-based races more effectively than the state of the art.

The IFDS algorithm can be compute-and memoryintensive for some large programs, often running for a long time (more than expected) or terminating prematurely after some time and/or memory budgets have been exhausted. In the latter case, the corresponding IFDS data-flow analyses may suffer from false negatives and/or false positives. To improve this, we introduce a sparse alternative to the traditional IFDS algorithm. Instead of propagating the data-flow facts across all the program points along the program’s (interprocedural) control flow graph, we propagate every data-flow fact directly to its next possible use points along its own sparse control flow graph constructed on the fly, thus reducing significantly both the time and memory requirements incurred by the traditional IFDS algorithm. In our evaluation, we compare FLOWDROID, a taint analysis performed by using the traditional IFDS algorithm, with our sparse incarnation, SPARSEDROID, on a set of 40 Android apps selected. For the time budget (5 hours) and memory budget (220GB) allocated per app, SPARSEDROID can run every app to completion but FLOWDROID terminates prematurely for 9 apps, resulting in an average speedup of 22.0x. This implies that when used as a market-level vetting tool, SPARSEDROID can finish analyzing these 40 apps in 2.13 hours (by issuing 228 leak warnings) while FLOWDROID manages to analyze only 30 apps in the same time period (by issuing only 147 leak warnings).

The frequent release of Android OS and its various versions bring many compatibility issues to Android Apps. This paper studies and addresses such evolution-induced compatibility problems. We conduct an extensive empirical study over 11 different Android versions and 4,936 Android Apps. Our study shows that there are drastic API changes between adjacent Android versions, with averagely 140.8 new types, 1,505.6 new methods, and 979.2 new fields being introduced in each release. However, the Android Support Library (provided by the Android OS) only supports less than 23% of the newly added methods, with much less support for new types and fields. As a result, 91.84% of Android Apps write additional code to support different OS versions. Furthermore, 88.65% of the supporting codes share a common pattern, which directly compares variable android.os.Build.VERSION.SDK_INT with a constant version number, to use an API of particular versions.

UnionPay's inter-bank transaction settlement platform (ITSP) generates a huge amount of bankcard transaction data everyday, recording different bankcard activities. In order to unleash the business value of these data, UnionPay has built a customized data warehouse based on Hadoop to manage and query the massive data imported from ITSP. However, the original system suffers from low storage utilization due to various types of data redundancy. Such data redundancy is caused by the long-term evolution of the system architecture. It dramatically wastes storage space, degrades query performance and leads to data inconsistency problem. In order to address these issues, we have developed UStore, an optimized storage system to reduce most data redundancies and improve query performance. In this paper, we present the design and implementation of UStore in detail. We test the performance of UStore on UnionPay's real data and the results show significant improvements in both storage utilization and query performance. To date, UStore has been deployed to process over 15 years' bankcard transaction data (over 3PB in plain text format) in UnionPay.