---
breadcrumbs:
- - /developers
  - For Developers
- - /developers/testing
  - Testing and infrastructure
page_name: instrumented-libraries-for-dynamic-tools
title: Instrumented libraries for dynamic tools
---

Instrumented libraries are a part of Chromium's development infrastructure. They
are intended to complement sanitizer tools
([AddressSanitizer](/developers/testing/addresssanitizer),
[MemorySanitizer](/developers/testing/memorysanitizer),
[ThreadSanitizer](/developers/testing/threadsanitizer-tsan-v2)).

Only Ubuntu Trusty x86_64 is supported at this time.

## Overview

Sanitizer tools rely on compile-time instrumentation. However, Chromium code may
call into system-installed third-party shared libraries, which were not built
with the appropriate instrumentation. This is a problem:

*   bugs in third-party libraries, which may affect Chromium, go undetected,
*   certain Chromium bugs may go undetected (e.g. passing an invalid buffer to
    third-party code),
*   MemorySanitizer generates lots of bogus reports, which makes it unusable.
    This happens because MSan doesn't recognize any memory initialization which
    happens in uninstrumented code.

To avoid this issue, we've made it possible to make Chromium use
sanitizer-instrumented versions of third-party DSOs. By setting a GN flag, you
can either have them built from source during Chromium build, or download
pre-built binaries from Google Storage. The list contains ~50 third-party
packages, which should cover most of the DSO dependencies of Chrome and tests
(enough at least to run MSan without bogus reports).

## Using pre-built binaries

Follow the MemorySanitizer [instructions](/developers/testing/memorysanitizer).

Note that we don't provide pre-built binaries for every configuration. At this
point in time only MSan is supported, with `msan_track_origins` either 0 or 2.

## Building from source

[Instructions for rebuilding instrumented libraries.](https://chromium.googlesource.com/chromium/src.git/+/main/docs/linux/instrumented_libraries.md)

## Adding new packages

You'll need to ping earthdok@ or glider@ to do this. The information below is
for reference.

To add a new package, you need to do the following:

*   get OSS compliance approval,
*   add a new target to `third_party/instrumented_libraries/BUILD.gn`,
*   add the package to
    `third_party/instrumented_libs/scripts/install-build-deps.sh`,
*   make sure it builds and works on Focal (i.e. where applicable),
*   update the pre-built binaries.

Usually you want to use the same configure flags that `debian/rules` uses.

To rebuild the binaries, follow the instructions for [Building from source](#building-from-source).