2.2 Test Generation with Symbolic Execution. A simple example of their difference: concurrency. Symbolic execution is a powerful technique to systematically explore paths (possibly all) of a software program. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): We present results for the "Impact Project Focus Area " on the topic of symbolic execution as used in software testing. Symbolic execution is a program analysis technique that was introduced in the 70s (e.g., see [14, 37, 76, 79, 103]). Symbolic Execution King [Comm. To ensure feasibil-ity of symbolic execution, even small programs must cur- Before we describe compilation-based symbolic execution in detail, this section summarizes some relevant background information. A simple example of their difference: concurrency. All paths in the program form its execution tree, in which some paths are feasible and some are infeasible. Applications of Symbolic Execution General goal:Reason about behavior of program Basic applications Detectinfeasible paths Generatetest inputs Findbugsand vulnerabilies Advanced applications Generating program invariants Prove that two pieces of code are equivalent Debugging Automated program repair 12 Problems of Symbolic Execution In this paper, we investigate the problem of automatically generating test cases that trigger the worst-case execution of programs and propose a novel technique that solves this problem with an unprecedented combination of symbolic execution and evolutionary algorithms. In symbolic execution, a pro-gram is executed using symbolic variables in place of con-crete values for inputs. Software testing is one of the most popular validation techniques in the software industry. However, the scal-ability of symbolic execution is often limited by path explosion, i.e., the number of symbolic states representing the paths under exploration quickly explodes as execution goes on. This path condition characterizes the set of all . Symbolic execution is a natural extension of normal execution, providing the normal computations as a special case. AFL and libFuzzer. Symbolic execution is an automated technique for program testing that has recently become practical, thanks to advances in constraint solvers. Unlike concrete execution, where the taken path is determined by the input, in symbolic execution the program can take any feasible path. SAFL: Increasing and Accelerating Testing Coverage with Symbolic Execution and Guided Fuzzing. 4: Symbolic Execution . Different flavors of the symbolic analysis of the software include, but are not limited to, concolic testing [10,11], symbolic execution [12, 13], and symbolic interpretation [14]. Symbolic execution and program testing Commun. Viewed as a kind of static analysis, symbolic execution is complete in that whenever a symbolic executor claims to have found a bug, the claim is true. Symbolic Execution and Program Testing James C. King IBM Thomas J. Watson Research Center This paper describes the symbolic execution of pro- grams. Use symbolic execution to verify a use indicated function in the program. Concolic testing overcomes these problems by combining concrete execution (i.e. If execution path depends on unknown, we fork symbolic executor at least, conceptually 5 Symbolic Execution Example 5 1.int a = , b = , c = ; 2.// symbolic Second, Symbolic execution is an automated technique for program testing that has recently become practical, thanks to advances in constraint solvers. King ACM , 19(7), 385-394 Published February 15, 1976 J.
It may be used in the generation of test data, in program proving, and in program reduction. Concolic testing overcomes these problems by combining concrete execution (i.e. Performance profiling can benefit from test cases that hit high-cost executions of programs. K. Serebryany et al. It intertwines traditional symbolic execution [16] with concrete execution, and explores as many program paths as possible to generate test cases by solving path constraints. Symbolic Execution and Program Testing JAMES C.KING IBM THOMAS J.WASTON RESEARCH CENTER PRESENTED BY: MENG WU 1/23 History of Symbolic Execution Robert S. Boyer, Bernard Elspas, and Karl N. Levitt. symbolic execution [14, 26, 1, 13, 25, 2, 27, 8, 24] addresses the problem of poor test coverage. ferential testing within a single symbolic execution engine; 3)A toolkit implementing our approach together with com-prehensive case studies on three symbolic execution enginesKLEE, CREST and FuzzBALLimplementing different styles of symbolic execution (e.g. However, when a part of the path condition is infeasible for the SMT solver to handle, we substitute values from a test run of the program. At the other end of the spectrum, the most precise form of automatic code-driven test generation known today is dynamic test generation with symbolic execution. Symbolic execution is a powerful technique for analyz-ing program behavior, nding bugs, and generating tests, but suffers from severely limited scalability: the largest pro-grams that can be symbolically executed today are on the order of thousands of lines of code. When symbolic exe- This paper describes a practical approach between these two extremes Each symbolic execution result may be equivalent to a large number of normal tests" Skilled in Program Analysis and Verification Techniques such as Symbolic Execution, C, C++, CLPR, Logic Programming, Python. Concolic execution explores a program by running it on concrete input values, for example x = 0 and u = 1.0, and at the same time using symbolic execution to collect the constraints of the followed program path. Dynamic execution of program Observe behavior Compare against expected behavior e.g. CACM, 19(7):385-394, 1976. I did my Ph.D. and PostDoc at National University of Singapore (Class . Surprisingly, we can only find a few approaches to testing in the context of logic programming. ATG with Fuzzing. Symbolic execution . First, we dene a source to source translation to instrument a program, which enables standard model checkers to perform symbolic execution of the program. 1 The tool that . Symbolic execution and program testing. Abstract: We present results for the "Impact Project Focus Area" on the topic of symbolic execution as used in software testing. The advanced method of symbolic evaluation can be applied to program testing situations with results close to those of formal correctness proofs?but without the high cost. On the Danger of Coverage Directed Test Case Generation. We describe techniques for unit testing based on symbolic execution. Symbolic Execution King [Comm. A Survey of Symbolic Execution . Symbolic-execution-based guidance.
The video shows how to use the klee_make_symbolic function to symbolise memory, how KLEE generates multiple test cases that explore different execution paths in the program and how we can use the KLEE ktest-tool to inspect the concrete values of the symbolic data. AddressSanitizer Algorithm . To solve this problem, recent studies have proposed hybrid fuzzers that observe the context of a target program using symbolic execution; these fuzzers generate test cases to bypass the sanity check. A Software Engineer and Researcher with a demonstrated history of working on Program Analysis, Resource Analysis, Program Testing, and LLVM Compilers. concolic vs. keeping all paths in memory, interpretation vs. instrumen- . Concolic Testing Dynamic Symbolic Execution Marco Probst Albert-Ludwigs-Universitt Freiburg January 25th, 2016 Marco Probst Concolic Testing 1 / 22. SELECT-a formal system for testing and debugging programs by symbolic execution. We review, compare and discuss several approaches for representing programs by logic formulas, such as symbolic model checking, bounded model checking, verification-condition generation, and symbolic-execution-based test generation. Dynamic symbolic execution consists in executing the program, starting with arbitrary inputs, while performing a symbolic execution in parallel to collect sym- "Program testing and program proving can be considered as extreme alternatives. tive whitebox fuzz testing approach inspired by recent ad-vances in symbolic execution and dynamic test generation. 2.1 Symbolic execution At its core, every implementation of symbolic execution is constructed from a set of basic building blocks (see Figure1): Execution The program under test is executed, and the sys- This is despite the high promises that the symbolic execution technique engendered when it was first proposed as a method for automatic test data generation . Random Testing and Dynamic Symbolic Execution. Symbolic execution is a program analysis technique introduced in the 70s that has received renewed interest in recent years, due to algorithmic advances and increased availability of computational power and constraint solving technology. The video then goes through several of the examples from the KLEE website and . Week 4: output or "do not crash" Marco Probst Concolic Testing 8 / 22. In computer science, symbolic execution (also symbolic evaluation or symbex) is a means of analyzing a program to determine what inputs cause each part of a program to execute. To explore another path in the program, concolic execution derives a Symbolic execution is a software testing technique that is useful to aid the generation of test data and in proving the program quality. Symbolic execution: basic idea 8 Execute the program on symbolic values. symbolic execution is typically used in software testing to explore as many different program paths as possible in a given amount of time, and for each path to generate a set of concrete input values exercising it, and check for the presence of various kinds of errors including assertion violations, uncaught exceptions, security vulnerabilities, symbolic execution, a description of the three fundamental prob-lems, and a summary of existing well known techniques that ad-dress those problems. We provide a two-fold generalization of tra-ditional symbolic execution based approaches. During execution, a symbolic execution engine accumulates a set of constraints on the symbolic inputs. James C. King. testing) with symbolic execution.1 Symbolic execution is used to solve for inputs that lead along a certain path. I am a Distinguished Engineer at Lacework . This work proposes that a program can be more effectively tested by executing it "symbolically" by supplying specific constants as input values to a program being tested, and designed and implemented an interactive debugging/testing system called EFFIGY. Let us consider a simple programming language. u = 1.0, and at the same time using symbolic execution to collect the constraints of the followed program path. 2 Dynamic Symbolic Execution 2.1 Introduction Dynamic symbolic execution [22,5] is a variation of conventional static symbolic ex-ecution [24]. Symbolic execution has several applications mainly in the validation of software. Symbolic execution [10, 22] is another classical technique for software testing and analysis. 3: AddressSanitizer. In ICRS, pages 234- 245, 1975. The paper Symbolic execution and program testing of James C. King gives you a nice intro on symbolic execution topic; Slides from this Harvard course are useful to visualize symbolic execution with nice figures and examples; Dynamic Binary Analysis and Instrumentation Covering a function using a DSE approach by Jonathan Salwan. The execution proceeds as in a normal execution except that values may be symbolic formulas over the input symbols. Each conditional expression in the program represents a constraint that determines an execu-tion path. DEMO - Demonstrations . Symbolic execution has several applications mainly in the validation of software. The collected constraints are Each conditional expression in the program represents a constraint that determines an execu-tion path. Welcome to my web-page! Before joining Lacework in 2022, I was a Partner Researcher at Microsoft Research from 2006 to 2021, and before that, I was a Distinguished Member of the Technical Staff . Abstract: Worst-case execution time testing amounts to constructing a test case triggering the worst-case execution time of a program, and has many important applications to identify, debug and fix performance bottlenecks and security holes of programs. Large-Scale Concolic Testing SAGE: Concolic testing tool developed at Microsoft Research Test robustness against unexpectedinputs read from les, e.g., Audio les read by media player Ofce documents read by MS Ofce Start with known input les and handlebytes read from les as symbolic input Use concolic execution to compute variants of these les During symbolic execution, program state consists of - symbolic values for some memory locations An interpreter follows the program, assuming symbolic values for inputs rather than obtaining actual inputs as normal execution of the program would. Viewing symbolic execution as a kind of testing. numbers) one supplies symbols representing arbitrary values. Dynamic Symbolic Execution [14], [15] (DSE) is a widely accepted and effective approach for automatic test data gener-ation. a key goal of symbolic execution in the context of soft- ware testing is to explore as many different program paths as possible in a given amount of time, and for each path to (1) generate a set of concrete input values exercising that path, and (2) check for the presence of various kinds of errors including assertion violations, uncaught Steps to use Symbolic Execution: The execution requires a selection of paths that are exercised by a set of data values. In symbolic execution, a program is executed using symbolic variables in place of con-crete values for inputs. In symbolic execution you only provide your program and the symbolic execution engine will examine all the feasible paths to generate test inputs or check assertions. AddressSanitizer: A Fast Address Sanity Checker. SELECT-a formal system for testing and debugging programs by symbolic execution. Our approach records an actual run of the program un-der test on a well-formed input, symbolically evaluates the recorded trace, and gathers constraints on inputs capturing how the program uses these. Symbolic execution is a program analysis technique introduced in the 70s that has received renewed interest in recent years, due to algorithmic advances and increased availability of . Symbolic Execution and Program Testing. SE comes as a modular library that gives virtual machines symbolic execution and program analysis capabilities. A program, which is executed using actual data, results in the output of a series of values. Symbolic execution is a white-box technique that executes a program symbolically, computes constraints along different paths, and uses a constraint solver to generate inputs that satisfy the collected constraints along each path. Symbolic Execution for GUI Testing Svetoslav Ganov Laboratory of Experimental Software Engineering University of Texas at Austin 001-832-366-4884 . However, without prior knowledge of the target program, the fuzzer can generate only a limited number of test cases because of sanity checks. def f . Lecture in the "Program Analysis" course by Prof. Dr. Michael Pradel at University of Stuttgart in winter semester 2020/21See course page for more informatio. Early work on symbolic execution Robert S. Boyer, Bernard Elspas, and Karl N. Levitt. Symbolic execution allows us to systematically consider many of these paths. It may be used in the generation of test data, in program proving, and in program reduction. "Program testing and program proving can be considered as extreme alternatives. Symbolic Execution: The term symbolic execution refers to an execution or run of a program P on sym-bolic inputs (i.e., inputs are not concrete) but instead range over all values from the input domain of the program P. Symbolic execution of a program P can be acheived on a computer by executing the program P symbolically using an interpreter or a symbolic virtual machine, e.g., the KLEE . Instead of using concrete in-put, symbolic execution uses symbolic values as input and explores a program's execution space. The advanced method of symbolic evaluation can be applied to program testing situations with results close to those of formal correctness proofs?but without the high cost. Symbolic Execution and Program Testing (2/2) We can prove the correctness of each path by executing it symbolically as follows: Place ASSUME at the beginning of the path and PROVE at the end of the path Execute the path symbolically If the PROVE at the end of the path displays true, the path is correct, otherwise it is not Symbolic execution then automatically explores hundreds of thousands of paths through the system, while analyzers . testing) with symbolic execution.1 Symbolic execution is used to solve for inputs that lead along a certain path. We propose a novel technique for worst-case execution time testing combining symbolic execution and evolutionary algorithms, which we call . Computational definitions for the basic operators of the language are extended to accept symbolic inputs and produce symbolic formulas as output. Path condition is a logical formula over the symbolic inputs that encodes all branch decisions taken so far. Unit tests are popular, but it is an art to write them in a way that specifies a program's behavior well and it is laborious to write enough of them to have confidence in the correctness of an implementation. This paper describes a practical approach between these two extremes Each symbolic execution result may be equivalent to a large number of normal tests" Instead of using concrete inputs, symbolic execution executes a program with symbolic inputs. Complete coverage of the program would be all of its paths. executions and increases test coverage is symbolic execu-tion [1,3,9,22,23,27,28,30]. Symbolic execution for software testing: three decades later Computer systems organization Architectures Parallel architectures Multiple instruction, multiple data General and reference Cross-computing tools and techniques Verification Software and its engineering Software creation and management Software development process management I think symbolic execution can be used in many other interesting ways Next: Symbolic execution as Empirical studies tool Web application security checker Enhancement to abstraction-based static analysis Program synthesis tool All of these take advantage of sym exec strengths, and try to avoid drawbacks 7 Model checking can handle multi-thread systems because it is specified in the FSM provided as input, however, symbolic execution . ACM 1976] Analysis of programs with unspecied inputs -Execute a program on symbolic inputs Symbolic states represent sets of concrete states For each path, build a path condition -Condition on inputs - for the execution to follow that path Instead of supplying the normal inputs to a program (e.g. In symbolic execution you only provide your program and the symbolic execution engine will examine all the feasible paths to generate test inputs or check assertions. Abstract: We present results for the "Impact Project Focus Area" on the topic of symbolic execution as used in software testing. ACM 1976] Analysis of programs with unspecied inputs -Execute a program on symbolic inputs Symbolic states represent sets of concrete states For each path, build a path condition -Condition on inputs - for the execution to follow that path The execution proceeds as in a The paper is a tutorial on symbolic execution and how it may be used in software testing and in particular the testing of commercial data-processing (DP) software. . Key idea: generalize testing by using unknown symbolic variables in evaluation Symbolic executor executes program, tracking symbolic state. R. Baldoni et al. A version of this paper was originally presented at the First International Workshop on Automated Program Analysis, Testing and Verification, held in Limerick, Ireland, 4-5 June 2000. . numbers) one supplies symbols represent- ing arbitrary values. Mingzhe Wang, Jie Liang, Yuanliang Chen, Yu Jiang, Xun Jiao, Han Liu, Xibin Zhao, Jiaguang Sun. Symbolic execution and program testing Commun. SE runs unmodified x86, x86-64, or ARM software stacks, including programs, libraries, the kernel, and drivers. 96 A System to Generate Test Data and Symbolically Execute Programs L. Clarke Computer Science To support the verification, add to the language two statements: . Symbolic execution is an approach that can help. Introduction to Symbolic Execution In contrast to black box test data generation approaches, which generate test data for a program without considering My area of expertise includes program analysis, testing, verification, security, and software engineering. We propose symbolic execution for The paper is a tutorial on symbolic execution and how it may be used in software testing and in particular the testing of commercial data-processing (DP) software. 3.1. Therefore, the ACM , 19(7), 385-394 Published February 15, 1976 J. the strongest techniques is concrete{symbolic (concolic1) execution [19, 31]. Model checking can handle multi-thread systems because it is specified in the FSM provided as input, however, symbolic execution . J.C. King. Symbolic Analysis and Test Generation. King Generally speak-ing, a symbolic executor interprets a program with symbolic inputs, systematically enumerating execution paths induced by the symbolic inputs and the program's control ow. Symbolic execution can also be used to generate input for differential testing. (most cited) Leon J. Osterweil and Lloyd D. Fosdick. Symbolic execution is a powerful technique that can generate tests steering program execution into desired paths. However, when a part of the path condition is infeasible for the SMT solver to handle, we substitute values from a test run of the program. The program is currently displayed in (GMT+02:00) Amsterdam, Berlin, Bern, Rome, .
Overview 1 Code Example . Symbolic execution and program testing. Symbolic state maps variables to symbolic values. Symbolic execution is a program analysis technique introduced in the 70s that has received renewed interest in recent years, due to algorithmic advances and increased availability of computational power and constraint solving technology. This paper describes the symbolic execution of programs. In this paper, we introduce a systematic approach for dynamic testing that combines both concrete and symbolic execution. Week 3: (Tuesday - Eric) MultiSE: Multi-Path Symbolic Execution using Value Summaries (Thursday - Eric A Survey of Symbolic Execution Techniques. Symbolic Execution Symbolic execution refers to execution of program with symbols as argument. Symbolic execution King, CACM 1976. Since program execution may depend on the user input, it is a challenge to select suitable values in a way that allows thorough testing. This path condition characterizes the set of all concrete inputs that drive the program down the followed path. Instead of supplying the normal inputs to a program (e.g. Observe that the feasible executions of a program Generally speak- ing, a symbolic executor interprets a program with symbolic inputs, systematically enumerating execution paths induced by the symbolic inputs and the program's control flow. It can be used for systematically testing a program and test input generation with high coverage. present a novel framework based on symbolic execution, for automated checking of such systems.