PR: https://gitlab.com/redhat/centos-stream/rpms/python-pip/-/merge_requests/13/

In order to test it:

Run this script to create a malformed tarball:

"""
import tarfile

def mkinfo(name, **kwargs):
    tarinfo = tarfile.TarInfo(name=name)
    for name, value in kwargs.items():
        setattr(tarinfo, name, value)
    return tarinfo

with tarfile.open('evil.tar.gz', 'w:gz') as tf:
    tf.addfile(mkinfo('./pyproject.toml'))
    tf.addfile(mkinfo('./tmp', type=tarfile.SYMTYPE,
                      linkname='../../../../../../../../tmp'))
    tf.addfile(mkinfo('./tmp/poc'))
"""

Do a python3 -m pip install evil.tar.gz

It will fail with: FileNotFoundError: [Errno 2] No such file or directory: '/tmp/pip-8lk56uxg-build/setup.py'

Whereas on the fixed pip it should reject the operation with:
"tarfile.OutsideDestinationError: 'tmp/poc' would be extracted to '/tmp/poc', which is outside the destination"

Verified on the PR.