| commit | 79b9e326a162b15ca5758ee214e350f4f7c038fe | [log] [tgz] |
|---|---|---|
| author | Pierre-Clément Tosi <ptosi@google.com> | Tue Oct 10 10:27:25 2023 +0100 |
| committer | David Gibson <david@gibson.dropbear.id.au> | Wed Oct 11 11:35:08 2023 +1100 |
| tree | dfffd69cba3b2988b957d625853e895c2f38ac60 | |
| parent | 52157f13ef3d45984ab17fd79bf0d9c69b57ae66 [diff] |
libfdt: fdt_get_alias_namelen: Validate aliases
Ensure that the alias found matches the device tree specification v0.4:
Each property of the /aliases node defines an alias. The property
name specifies the alias name. The property value specifies the full
path to a node in the devicetree.
This protects against a stack overflow caused by
fdt_path_offset_namelen(fdt, path, namelen)
calling
fdt_path_offset(fdt, fdt_get_alias_namelen(fdt, path, namelen))
leading to infinite recursion on DTs with "circular" aliases.
This fix was originally written by Mike McTernan for Android in [1].
[1]: https://android.googlesource.com/platform/external/dtc/+/9308e7f9772bd226fea9925b1fc4d53c127ed4d5
Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
Acked-by: Mike McTernan <mikemcternan@google.com>
Message-ID: <20231010092725.63h7c45p2fnmj577@google.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The source tree contains the Device Tree Compiler (dtc) toolchain for working with device tree source and binary files and also libfdt, a utility library for reading and manipulating the binary format.
dtc and libfdt are maintained by:
A Python library wrapping libfdt is also available. To build this you will need to install swig and Python development files. On Debian distributions:
$ sudo apt-get install swig python3-dev
The library provides an Fdt class which you can use like this:
$ PYTHONPATH=../pylibfdt python3
>>> import libfdt
>>> fdt = libfdt.Fdt(open('test_tree1.dtb', mode='rb').read())
>>> node = fdt.path_offset('/subnode@1')
>>> print(node)
124
>>> prop_offset = fdt.first_property_offset(node)
>>> prop = fdt.get_property_by_offset(prop_offset)
>>> print('%s=%s' % (prop.name, prop.as_str()))
compatible=subnode1
>>> node2 = fdt.path_offset('/')
>>> print(fdt.getprop(node2, 'compatible').as_str())
test_tree1
You will find tests in tests/pylibfdt_tests.py showing how to use each method. Help is available using the Python help command, e.g.:
$ cd pylibfdt $ python3 -c "import libfdt; help(libfdt)"
If you add new features, please check code coverage:
$ sudo apt-get install python3-coverage $ cd tests # It's just 'coverage' on most other distributions $ python3-coverage run pylibfdt_tests.py $ python3-coverage html # Open 'htmlcov/index.html' in your browser
The library can be installed with pip from a local source tree:
$ pip install . [--user|--prefix=/path/to/install_dir]
Or directly from a remote git repo:
$ pip install git+git://git.kernel.org/pub/scm/utils/dtc/dtc.git@main
The install depends on libfdt shared library being installed on the host system first. Generally, using --user or --prefix is not necessary and pip will use the default location for the Python installation which varies if the user is root or not.
You can also install everything via make if you like, but pip is recommended.
To install both libfdt and pylibfdt you can use:
$ make install [PREFIX=/path/to/install_dir]
To disable building the python library, even if swig and Python are available, use:
$ make NO_PYTHON=1
More work remains to support all of libfdt, including access to numeric values.