Yujia Chen

Deep Learning (DL)-based methods have proven to be effective for software vulnerability detection, with a potential for substantial productivity enhancements for detecting vulnerabilities. Current methods mainly focus on detecting single functions (i.e., intra-procedural vulnerabilities), ignoring the more complex inter-procedural vulnerability detection scenarios in practice. For example, developers routinely engage with program analysis to detect vulnerabilities that span multiple functions within repositories. In addition, the widely-used benchmark datasets generally contain only intra-procedural vulnerabilities, leaving the assessment of inter-procedural vulnerability detection capabilities unexplored. To mitigate the issues, we propose a holistic multi-level evaluation system, named VulEval, aiming at evaluating the detection performance of inter- and intra-procedural vulnerabilities simultaneously. Specifically, VulEval consists of three interconnected evaluation tasks: (1) Function-Level Vulnerability Detection, aiming at detecting intra-procedural vulnerability given a code snippet; (2) Vulnerability-Related Dependency Prediction, aiming at retrieving the vulnerable-related dependency from call graphs for providing developers with explanations about the vulnerabilities; and (3) Repository-Level Vulnerability Detection, aiming at detecting inter-procedural vulnerabilities by combining with the dependencies identified in the second task. VulEval also consists of a large-scale dataset, with a total of 4,196 CVE entries, 232,239 functions, and corresponding 4,699 repository-level source code in C/C++ programming languages. By evaluating 19 vulnerability detection methods on the data split randomly and by time respectively, we observe that the repository-level vulnerability detection framework outperforms the corresponding function-level methods, with an increase of 7.43% in precision, 3.38% in recall, 4.91% in F1 score, and 5.24% in MCC on average except for PILOT. It indicates that incorporating vulnerability-related dependencies facilitates vulnerability detection. Our experimental results also demonstrate that the performance of program-analysis- and prompt-based methods are not affected when splitting the data by time. In addition, our findings indicate that the split setting, retrieval techniques, and vulnerability types have substantial impacts on the performance of repository-level vulnerability detection. We conclude our insights and takeaways for researchers and developers for software vulnerability detection in practice.

Large code models (LCMs) have remarkably advanced the field of code generation. Despite their impressive capabilities, they still face practical deployment issues, such as high inference costs, limited accessibility of proprietary LCMs, and adaptability issues of ultra-large LCMs. These issues highlight the critical need for more accessible, lightweight yet effective LCMs. Knowledge distillation (KD) offers a promising solution, which transfers the programming capabilities of larger, advanced LCMs (Teacher) to smaller, less powerful LCMs (Student). However, existing KD methods for code intelligence often lack consideration of fault domain knowledge and rely on static seed knowledge, leading to degraded programming capabilities of student models. In this paper, we propose a novel Self-Paced knOwledge DistillAtion framework, named SODA, aiming at developing lightweight yet effective student LCMs via adaptively transferring the programming capabilities from advanced teacher LCMs. SODA consists of three stages in one cycle: (1) Correct-and-Fault Knowledge Delivery stage aims at improving the student model’s capability to recognize errors while ensuring its basic programming skill during the knowledge transferring, which involves correctness-aware supervised learning and fault-aware contrastive learning methods. (2) Multi-View Feedback stage aims at measuring the quality of results generated by the student model from two views, including model-based and static tool-based measurement, for identifying the difficult questions; (3) Feedback-based Knowledge Update stage aims at updating the student model adaptively by generating new questions at different difficulty levels, in which the difficulty levels are categorized based on the feedback in the second stage. By performing the distillation process iteratively, the student model is continuously refined through learning more advanced programming skills from the teacher model. We compare SODA with four state-of-the-art KD approaches on three widely-used code generation benchmarks with different programming languages. Experimental results show that SODA improves the student model by 65.96% in terms of average Pass@1, outperforming the best baseline PERsD by 29.85%. Based on the proposed SODA framework, we develop SodaCoder, a series of lightweight yet effective LCMs with ∼7B parameters, which outperform 15 LCMs with less than or equal to 16B parameters. Notably, SodaCoder-DS-6.7B, built on DeepseekCoder-6.7B, even surpasses the prominent ChatGPT on average Pass@1 across seven programming languages (66.4 vs. 61.3).

In the field of code intelligence, effectively modeling long-range code poses a significant challenge. Existing pre-trained language models (PLMs) such as UniXcoder have achieved remarkable success, but they still face difficulties with long code inputs. This is mainly due to their limited capacity to maintain contextual continuity and memorize the key information over long-range code. To alleviate the difficulties, we propose EXPO, a framework for EXtending Pre-trained language models for lOng-range code. EXPO incorporates two innovative memory mechanisms we propose in this paper: Bridge Memory and Hint Memory. Bridge Memory uses a tagging mechanism to connect disparate snippets of long-range code, helping the model maintain contextual coherence. Hint Memory focuses on crucial code elements throughout the global context, such as package imports, by integrating a 𝑘NN attention layer to adaptively select the relevant code elements. This dual-memory approach bridges the gap between understanding local code snippets and maintaining global code coherence, thereby enhancing the model’s overall comprehension of long code sequences. We validate the effectiveness of EXPO on five popular pre-trained language models such as UniXcoder and two code intelligence tasks including API recommendation and vulnerability detection. Experimental results demonstrate that EXPO significantly improves the pre-training language models.

Open-Source Software (OSS) vulnerabilities bring great challenges to the software security and pose potential risks to our society. Enormous efforts have been devoted into automated vulnerability detection, among which deep learning (DL)-based approaches have proven to be the most effective. However, the performance of the DL-based approaches generally relies on the quantity and quality of labeled data, and the current labeled data present the following limitations: (1) Tangled Patches: Developers may submit code changes unrelated to vulnerability fixes within patches, leading to tangled patches. (2) Lacking Inter-procedural Vulnerabilities: The existing vulnerability datasets typically contain function-level and file-level vulnerabilities, ignoring the relations between functions, thus rendering the approaches unable to detect the inter-procedural vulnerabilities. (3) Outdated Patches: The existing datasets usually contain outdated patches, which may bias the model during training. To address the above limitations, in this paper, we propose an automated data collection framework and construct the first repository-level high-quality vulnerability dataset named ReposVul. The proposed framework mainly contains three modules: (1) A vulnerability untangling module, aiming at distinguishing vulnerability-fixing related code changes from tangled patches, in which the Large Language Models (LLMs) and static analysis tools are jointly employed. (2) A multi-granularity dependency extraction module, aiming at capturing the inter-procedural call relationships of vulnerabilities, in which we construct multiple-granularity information for each vulnerability patch, including repository-level, file-level, function-level, and line-level. (3) A trace-based filtering module, aiming at filtering the outdated patches, which leverages the file path trace-based filter and commit time trace-based filter to construct an up-to-date dataset. The constructed repository-level ReposVul encompasses 6,134 CVE entries representing 236 CWE types across 1,491 projects and four programming languages. Thorough data analysis and manual checking demonstrate that ReposVul is high in quality and alleviates the problems of tangled and outdated patches in previous vulnerability datasets.

Developers often need to decide which APIs to use for the functions being implemented. With the ever-growing number of APIs and libraries, it becomes increasingly difficult for developers to find appropriate APIs, indicating the necessity of automatic API usage recommendation. Previous studies adopt statistical models or collaborative filtering methods to mine the implicit API usage patterns for recommendation. However, they rely on the occurrence frequencies of APIs for mining usage patterns, thus prone to fail for the low-frequency APIs. Besides, prior studies generally regard the API call interaction graph as homogeneous graph, ignoring the rich information (e.g., edge types) in the structure graph. In this work, we propose a novel method named MEGA for improving the recommendation accuracy especially for the low-frequency APIs. Specifically, besides call interaction graph , MEGA considers another two new heterogeneous graphs: global API co-occurrence graph enriched with the API frequency information and hierarchical structure graph enriched with the project component information. With the three multi-view heterogeneous graphs, MEGA can capture the API usage patterns more accurately. Experiments on three Java benchmark datasets demonstrate that MEGA significantly outperforms the baseline models by at least 19% with respect to the Success Rate@1 metric. Especially, for the low-frequency APIs, MEGA also increases the baselines by at least 55% regarding the Success Rate@1 score.