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The ESBMC model checker

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ESBMC (the Efficient SMT-based Context-Bounded Model Checker) is a mature, permissively licensed open-source context-bounded model checker that automatically detects or proves the absence of runtime errors in single- and multi-threaded C, C++, CUDA, CHERI, Kotlin, Python, and Solidity programs. It can automatically verify predefined safety properties (e.g., bounds check, pointer safety, overflow) and user-defined program assertions.

ESBMC supports:

  • The Clang compiler as its C/C++/CHERI/CUDA frontend;
  • The Soot framework via Jimple as its Java/Kotlin frontend;
  • The ast and ast2json modules as its Python frontend;
  • Implements the Solidity grammar production rules as its Solidity frontend;
  • Supports IEEE floating-point arithmetic for various SMT solvers.

ESBMC also implements state-of-the-art incremental BMC and k-induction proof-rule algorithms based on Satisfiability Modulo Theories (SMT) and Constraint Programming (CP) solvers.

We provide some background material/publications to help you understand exactly what ESBMC can offer. These are available online. For further information about our main components, check the ESBMC architecture.

Our main website is esbmc.org.

How to build/install ESBMC

Ubuntu 24.04

To compile ESBMC on Ubuntu 24.04 with LLVM 14 and the SMT solver Z3:

sudo apt update
sudo apt-get install -y clang-14 llvm-14 clang-tidy-14 python-is-python3 python3 git ccache unzip wget curl bison flex g++-multilib linux-libc-dev libboost-all-dev libz3-dev libclang-14-dev libclang-cpp-dev cmake
git clone https://github.com/esbmc/esbmc.git
cd esbmc
mkdir build && cd build
cmake .. -DENABLE_Z3=1
make -j4

Fedora 40

To compile ESBMC on Fedora 40 with the latest version of LLVM and the SMT solver Z3:

# Warning, the --allowerasing parameter will also remove incompatible packages to the packages specified below
sudo dnf install --best --allowerasing "@Development Tools" clang llvm llvm-devel clang-tools-extra python3 git ccache unzip wget curl bison flex gcc-c++ glibc-devel glibc-devel.i686 boost-devel boost-devel.i686 z3-devel clang-devel clang-devel.i686 cmake zlib-devel libffi-devel libstdc++-devel libstdc++-devel.i686
git clone https://github.com/esbmc/esbmc.git
cd esbmc
mkdir build && cd build
cmake .. -DENABLE_Z3=1 -DZ3_DIR=/usr/include/z3
make -j4

To build ESBMC with other operating systems and SMT solvers, please see the BUILDING file.

The user can also download the latest ESBMC binary for Ubuntu and Windows from the releases page.

FreeBSD

ESBMC should compile just fine in FreeBSD as long as the 32-bit libraries are enabled

pkg install git cmake python3 z3 bison flex boost-all
wget https://github.com/llvm/llvm-project/releases/download/llvmorg-16.0.0/clang+llvm-16.0.0-amd64-unknown-freebsd13.tar.xz && mv clang16
mkdir build && cd build
cmake .. -DLLVM_DIR=../clang16 -DClang_DIR=../clang16
make -j4

Mac OS X

M1/M2/M3/M4 Macs are now supported.

Given the common elements of OS X, run the script. It runs on both ARM and Intel macs. You do need homebrew installed. It creates the build folder, installs the Boolector SMT solver, and makes esbmc available globally. The script supports building the Python frontend as well. Note that the Python frontend is quite early in the support for Python.

 ./build-esbmc-mac.sh

The raw command is given here for reference.

cmake .. -DZ3_DIR=/opt/homebrew/Cellar/z3/4.13.4 -DENABLE_Z3=1 -DC2GOTO_SYSROOT=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -DLLVM_DIR=/opt/homebrew/opt/llvm/lib/cmake/llvm -DClang_DIR=/opt/homebrew/opt/llvm/lib/cmake/clang
make -j8
make install

Using the SMT Boolector Solver

Boolector is a fast solver and is recommended. To install Boolector, use the following one-line command:

git clone --depth=1 --branch=3.2.3 https://github.com/boolector/boolector && cd boolector && ./contrib/setup-lingeling.sh && ./contrib/setup-btor2tools.sh && ./configure.sh --prefix $PWD/../boolector-release && cd build && make -j9 && make install && cd .. && cd ..

Now rerun cmake,

cmake .. -DENABLE_Z3=1 -DENABLE_BOOLECTOR=1 -DBoolector_DIR=<the folder you ran the above command from>/boolector-release

We recommend using AMD64 via docker for a fully supported version on Mac OS X. We will soon remove this as native installations on Mac OS X ARM work well too. Sample docker-compose and docker files follow below.

FROM node:18-slim

## Install dependencies for ESBMC and other build tools
RUN apt-get update && apt-get install -y \
    clang-14 \
    llvm-14 \
    clang-tidy-14 \
    python-is-python3 \
    python3 \
    git \
    ccache \
    unzip \
    wget \
    curl \
    bison \
    flex \
    g++-multilib \
    linux-libc-dev \
    libboost-all-dev \
    libz3-dev \
    libclang-14-dev \
    libclang-cpp-dev \
    cmake \
    && rm -rf /var/lib/apt/lists/*

# Keep the container running with tail -f /dev/null
CMD ["bash", "-c", "tail -f /dev/null"]

Docker compose file:

version: '3.8'
services:
  esbmc:
    platform: linux/amd64
    build:
      context: .
      dockerfile: Dockerfile  # Assuming your Dockerfile is named `Dockerfile`
    tty: true
    stdin_open: true

The Linux/Amd64 line is very important for virtualizing Amd64. Now do docker-compose up --build. You can then follow the Linux instructions. Make -j16 works well on M2 mac's and beyond.

How to use ESBMC

As an illustrative example to show some of the ESBMC features, consider the following C code:

#include <stdlib.h>
int *a, *b;
int n;
#define BLOCK_SIZE 128
void foo () {
  int i;
  for (i = 0; i < n; i++)
    a[i] = -1;
  for (i = 0; i < BLOCK_SIZE - 1; i++)
    b[i] = -1;
}
int main () {
  n = BLOCK_SIZE;
  a = malloc (n * sizeof(*a));
  b = malloc (n * sizeof(*b));
  *b++ = 0;
  foo ();
  if (b[-1])
  { free(a); free(b); }
  else
  { free(a); free(b); }
  return 0;
}

Here, ESBMC is invoked as follows:

$esbmc file.c --incremental-bmc

Where file.c is the C program to be checked, and --incremental-bmc selects the incremental BMC strategy. The user can choose the SMT solver, property, and verification strategy. Note that you need math.h installed on your system, especially if you run a release version; build-essential typically covers math.h.

For this particular C program, ESBMC provides the following output as the verification result:

[Counterexample]


State 1 file memory.c line 14 column 3 function main thread 0
----------------------------------------------------
  a = (signed int *)(&dynamic_1_array[0])

State 2 file memory.c line 15 column 3 function main thread 0
----------------------------------------------------
  b = (signed int *)0

State 3 file memory.c line 16 column 3 function main thread 0
----------------------------------------------------
Violated property:
  file memory.c line 16 column 3 function main
  dereference failure: NULL pointer


VERIFICATION FAILED

Bug found (k = 1)

We refer the user to our documentation webpage for further examples of the ESBMC's features.

Using Config Files

ESBMC supports specifying options through TOML-formatted config files. To use a config file, export an environment variable:

export ESBMC_CONFIG_FILE="path/to/config.toml"

If no environment file is specified, then the default locations will be checked:

  • Windows: %userprofile%\esbmc.toml
  • UNIX: ~/.config/esbmc.toml

If nothing is found, then nothing is loaded. If you set the environment variable to the empty string, then it disables the entire config file loading process.

export ESBMC_CONFIG_FILE=""

An example of a config file:

interval-analysis = true
goto-unwind = true
unlimited-goto-unwind = true
k-induction = true
state-hashing = true
add-symex-value-sets = true
k-step = 2
floatbv = true
unlimited-k-steps = false
max-k-step = 100
memory-leak-check = true
context-bound = 2

Features

ESBMC detects errors in software by simulating a finite prefix of the program execution with all possible inputs. Classes of implementation errors that can be detected include:

  • User-specified assertion failures
  • Out-of-bounds array access
  • Illegal pointer dereferences, such as:
    • Dereferencing null
    • Performing an out-of-bounds dereference
    • Double-free of malloc'd memory
    • Misaligned memory access
  • Integer overflows
  • Undefined behavior on shift operations
  • Floating-point for NaN
  • Divide by zero
  • Memory leaks

Concurrent software (using the pthread API) is verified by explicitly exploring interleavings, producing one symbolic execution per interleaving. By default, pointer-safety, array-out-of-bounds, division-by-zero, and user-specified assertions will be checked for; one can also specify options to check concurrent programs for:

  • Deadlock (only on pthread mutexes and conditional variables)
  • Data races (i.e., competing writes)
  • Atomicity violations at visible assignments
  • Lock acquisition ordering

By default, ESBMC performs a "lazy" depth-first search of interleavings -- it can also encode (explicitly) all interleavings into a single SMT formula.

Many SMT solvers are currently supported:

  • Z3 4.13+
  • Bitwuzla
  • Boolector 3.0+
  • MathSAT
  • CVC4
  • CVC5
  • Yices 2.2+

In addition, ESBMC can be configured to use the SMTLIB interactive text format with a pipe to communicate with an arbitrary solver process, although there are not insignificant overheads involved.

Tutorials

We provide a short video that explains ESBMC:

https://www.youtube.com/watch?v=uJ5Jn0sxm08&t=2182s

In a workshop between Arm Research and the University of Manchester, this video was delivered as part of a technical talk on exploiting the SAT revolution for automated software verification.

We offer a post-graduate course in software security that explains the internals of ESBMC.

https://ssvlab.github.io/lucasccordeiro/courses/2020/01/software-security/index.html

This course unit introduces students to basic and advanced approaches to formally building verified trustworthy software systems, where trustworthiness comprises five attributes: reliability, availability, safety, resilience and security.

Selected Publications

Awards

  • Distinguished Paper Award at ASE'24
  • 35 awards from international competitions on software verification (SV-COMP) and testing (Test-Comp) 2012-2024 at TACAS/FASE (Strength: Bug Finding and Code Coverage).
  • Most Influential Paper Award at ASE’23
  • Best Tool Paper Award at SBSeg'23
  • Best Paper Award at SBESC’15
  • Distinguished Paper Award at ICSE’11

ESBMC-CHERI Video & Download

This video describes how to obtain, build and run ESBMC-CHERI on an example.

A pre-compiled binary for Linux is available in the pre-release ESBMC-CHERI, for other systems/archs the BUILDING.md document explains the necessary installation steps.

Open source

ESBMC is open-source software mainly distributed under the Apache License 2.0. It contains a significant amount of other people's software. However, please take a look at the COPYING file to explain who owns what and under what terms it is distributed.

We'd be extremely happy to receive contributions to improve ESBMC (under the terms of the Apache License 2.0). Please file a pull request against the public GitHub repo if you'd like to submit anything. General discussion and release announcements will be made via GitHub. Please post an issue on GitHub and contact us about research or collaboration.

Please review the developer documentation if you want to contribute to ESBMC.

Differences from CBMC

ESBMC is a fork of CBMC v2.9 (2008), the C Bounded Model Checker. The primary differences between the two are described here.

Acknowledgments

ESBMC is a joint project of the Federal University of Amazonas (Brazil), the University of Manchester (UK), the University of Southampton (UK), and the University of Stellenbosch (South Africa).

The ESBMC development was supported by various research funding agencies, including CNPq (Brazil), CAPES (Brazil), FAPEAM (Brazil), EPSRC (UK), Royal Society (UK), British Council (UK), European Commission (Horizon 2020), foundations including Lattice, Rust, Ethereum, and companies including ARM, Intel, Motorola Mobility, Nokia Institute of Technology and Samsung. The ESBMC development is currently funded by ARM, EPSRC grants EP/T026995/1 and EP/V000497/1, Ethereum Foundation, Rust Foundation, EU H2020 ELEGANT 957286, Intel, Motorola Mobility (through Agreement N° 4/2021), Soteria project awarded by the UK Research and Innovation for the Digital Security by Design (DSbD) Programme, and XC5 Hong Kong Limited.

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The efficient SMT-based context-bounded model checker (ESBMC)

esbmc.org/

Topics

kotlin python c cpp smt-solver k-induction automated-testing incremental-learning bmc solidity-contracts cheri automated-verification cp-solver

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