Klever 3.6

Added by Evgeny Novikov 10 days ago

Klever 3.6 was released pretty soon after Klever 3.5 since we updated Clade and CIF in the backward incompatible manner. This means that the new version of Klever requires all build bases to be regenerated with the new version of Clade and CIF installed together with Klever. You can download build bases for Linux 5.5.19, 5.10.120 and 5.17.13 as well as sample build bases prepared ahead of time. Corresponding files are available either directly from the "Files" tab or from the Klever tutorial.

Other changes in Klever 3.6 are new models for struct_size() and underlying __ab_c_size() for the Linux kernel.

Klever 3.5

Added by Evgeny Novikov about 1 month ago

We released Klever 3.5 that has following noticeable changes:

  • Improving support for verification of Linux 5.10 and Linux 5.17 (new specifications set "5.17" was added).
  • Environment models generated at verification of Linux loadable kernel modules do not contain infinite loops anymore. This accelerated analysis and did not result in any degradation in the quality of verification results.
  • Using Ubuntu 20.04, Debian 11 and openSUSE 15.3 as preferable Linux distributions for deployment of Klever.
  • Switching to Python 3.10. You should carefully read this comment if you are going to update existing local instances of Klever.
  • Supporting regular expressions for assessing unsafes (you can see #11513 for more details).
  • Updating Klever Tutorial, in particular using verification of loadable kernel modules of Linux 5.5 as an example.
  • Updating add-ons and verification back-ends (various bug fixes and optimizations).
  • More advanced authorization of new users. Now the administrator should activate new users while somebody should grant them access to some jobs.

Many thanks to everybody involved!

Klever 3.4

Added by Evgeny Novikov 4 months ago

Klever 3.4 includes the following prominent features:

  • Several improvements contributing development and generation of environment models:
    • Ability to specify savepoints for the main process.
    • Ability to select scenarios for particular savepoints manually.
    • Ability to configure the number of iterations for invocation of callbacks.
    • Providing users with a graphical representation of environment models directly in the Klever web UI.
  • Models for kmem_cache functions for the Linux kernel.
  • Updating add-ons and verification back-ends (various bug fixes and optimizations).
  • New sections in the user documentation: Configuring Program Decomposition and Development of Verifier Profiles.
  • Besides, you can find the CIF’s user documentation that may be helpful at development of advanced specifications and models.
  • Many fixes and minor improvements that make the specification development and verification workflow more easy, correct and reliable.

We highly appreciate efforts of developers and the feedback from users who made this release possible!

Klever top contributor Ilja Zakharov started a new job

Added by Evgeny Novikov 7 months ago

Ilja Zakharov was one of the greatest contributors to the Klever project. He was the primary developer of such components as Environment Model Generator, Program Fragment Generator, Schedulers and Controller. Besides, he created a lot of environment model specifications for different kinds of target programs and made considerable scientific researches. We appreciate his work very much.

Recently Ilja Zakharov became a Verification Engineer at the Runtime Verification company. There he will be engaged in application of formal methods for smart contracts and tools used for their verification. We wish him good luck and hope that the gained experience will help him at the new position.

Klever 3.3

Added by Evgeny Novikov 9 months ago

The most noticeable work in Klever 3.3 is a new section Development of Environment Model Specifications in the user documentation. Besides, there are following considerable improvements:

  • Fixing allocation of memory for arguments of callbacks of several vital Linux device driver types.
  • Enhancing environment model specifications for file systems.
  • Simplifying development of environment model specifications and fixing some bugs at their processing
  • Numerous enhancements of the Klever web UI that simplify several common use cases.
  • Updating dependencies and addons that make them more functional and robust.
  • Development of unit tests for deployment of Klever within the OpenStack cloud
  • Supporting deployment at openSUSE.
  • New section Development of Common API Models in the user documentation.

We would like to thank those developers and users who actively contributed to Klever 3.3!

Klever 3.2

Added by Evgeny Novikov 11 months ago

The major improvement of Klever 3.2 is a new environment model generator that supports automated splitting of complex environment models into sets of smaller ones. This is extremely helpful at verification of large programs and program fragments when verification tools often can not provide definite answers within specified time limits.

Other important changes are as follows:
  • Substantially fixed and enhanced representation of violation witnesses (error traces) and code coverage reports as well as navigation through them.
  • New environment models for the Linux kernel (the bitmap API and several functions working with strings).
  • New validation set on the base of faults found by Klever and fixed in the Linux kernel.
  • Supporting more reliable and efficient deployment of Klever within the OpenStack cloud.
  • New section Analysis of Code Coverage Reports in the Klever tutorial.

In addition, Klever 3.2 includes numerous minor improvements and bug fixes.

This release would not be possible without intensive work of developers and testers. Also, we always look forward and welcome a feedback from users.

Klever 3.1

Added by Evgeny Novikov over 1 year ago

Klever 3.1 was released!

The new release has the following major changes:

Many thanks to all contributors of Klever 3.1!

Klever 3.0

Added by Evgeny Novikov over 1 year ago

Let’s start the new year 2021 with new Klever 3.0!

Among a lot of improvements and bug fixes, most significant changes in Klever 3.0 are as follows:
  • Support for verification of kernel loadable modules of Linux 5.5.
  • Support for verification of Linux kernel loadable modules on the ARM architecture.
  • Fixing and developing specifications for verification of Linux kernel loadable modules:
    • Fixing specifications for checking usage of clocks in drivers.
    • Support for checking usage of the RCU API.
    • Developing detailed specifications for USB serial drivers.
    • Improving environment models for runtime power management callbacks.
    • Using device identifiers from the driver tables.
    • Developing models for devm memory allocating functions.
    • Fixing framebuffer_alloc/release models.
    • Adding models for request/release_firmware(), v4l2_i2c_subdev_init() and i2c_smbus_read_block_data().
  • More user-friendly configuration for target program fragments and requirement specifications.
  • Development of preset tags for assessing most common false alarms.
  • Support for new internal data formats for enhancing and optimizing representation and assessment of verification results.
  • Support for cross-references for original program source files and models.
  • Update of all variants of the CPAchecker verification back-end.
  • Switching to a special version of Frama-C developed within project Deductive Verification Tools for Linux Kernel from outdated and unmaintained CIL. Both tools are used for merging source files and optimizations like removing unused functions.
  • Using systemd scripts instead of init.d ones for Klever services.
  • Development of Tutorial

Klever 3.0 is not backward compatible with former versions of Klever, so, you need to remove existing instances if so and deploy Klever from scratch.

As usual many thanks are to everyone who participated in this release of Klever!

Klever 2.0

Added by Evgeny Novikov over 3 years ago

We are happy to announce that Klever 2.0 is released!

Klever 2.0 implements ideas suggested in [1]. In general we added support for verification of software written in the GNU C programming language. First examples of using Klever for software that differs from Linux device drivers are verification of Linux kernel subsystems [2] and BusyBox applets. We are looking forward for more success stories!

Most important changes in Klever 2.0 are the following:
  • Klever does not build programs under verification anymore. Instead it takes as input build bases that should be prepared with Clade in advance. This considerably speed ups verification when verifying the same software within different verification jobs. Also, this provides a more natural way to integrate Klever within a standard development life cycle.
  • The generator of program fragments (former verification objects) includes abstract means suitable for various software as well as means for particular kinds of programs that allow to avoid considerable efforts for configuring program decomposition.
  • The environment models generator consists of a number sub-generators that take specifications in suitable specific formats. This allows to simplify development of such the specifications very much. Besides, we fixed many existing and developed new environment model specifications both for new kinds of interactions between Linux kernel and BusyBox components and for new versions of the Linux kernel.
  • The Klever interface provides users with a extremely useful online editor that enables changing configuration and specification files directly within the interface.

As usual many minor improvements and bug fixes were included in Klever 2.0.

Klever 2.0 differs too much from previous versions of Klever. Therefore, we recommend to deploy it from scratch rather than to update existing deployments.

We would like to thank everybody who participated in development, testing and using of Klever!


  1. Novikov E., Zakharov I. (2018) Towards Automated Static Verification of GNU C Programs. In: Petrenko A., Voronkov A. (eds) Perspectives of System Informatics. PSI 2017. Lecture Notes in Computer Science, vol 10742. Springer, Cham.
  2. Novikov E., Zakharov I. (2018) Verification of Operating System Monolithic Kernels Without Extensions. In: Margaria T., Steffen B. (eds) Leveraging Applications of Formal Methods, Verification and Validation. Industrial Practice. ISoLA 2018. Lecture Notes in Computer Science, vol 11247. Springer, Cham.

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