[New-bugs-announce] [issue36596] tarfile module considers anything starting with 512 bytes of zero bytes to be a valid tar file

[Chris Siebenmann]

New submission from Chris Siebenmann <c.python01 at cs.toronto.edu>:

The easiest reproduction of this is:

    import tarfile
    tarfile.open("/dev/zero", "r:")

(If you use plain "r" you get a hang in attempted lzma decoding.)

I believe this is probably due to a missing 'elif self.offset == 0:' in the 'except EOFHeaderError' exception handling case that almost all of the other exception handlers have.

This appears to be a very long standing issue based on the history of the code.

----------
components: Library (Lib)
messages: 339915
nosy: cks
priority: normal
severity: normal
status: open
title: tarfile module considers anything starting with 512 bytes of zero bytes to be a valid tar file
versions: Python 2.7, Python 3.5, Python 3.6, Python 3.7, Python 3.8, Python 3.9

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue36596>
_______________________________________