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cpython/Misc
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Miss Islington (bot) 2cdbd3b8b2
bpo-45001: Make email date parsing more robust against malformed input (GH-27946) (GH-27973) 
Various date parsing utilities in the email module, such as
email.utils.parsedate(), are supposed to gracefully handle invalid
input, typically by raising an appropriate exception or by returning
None.

The internal email._parseaddr._parsedate_tz() helper used by some of
these date parsing routines tries to be robust against malformed input,
but unfortunately it can still crash ungracefully when a non-empty but
whitespace-only input is passed. This manifests as an unexpected
IndexError.

In practice, this can happen when parsing an email with only a newline
inside a ‘Date:’ header, which unfortunately happens occasionally in the
real world.

Here's a minimal example:

    $ python
    Python 3.9.6 (default, Jun 30 2021, 10:22:16)
    [GCC 11.1.0] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import email.utils
    >>> email.utils.parsedate('foo')
    >>> email.utils.parsedate(' ')
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "/usr/lib/python3.9/email/_parseaddr.py", line 176, in parsedate
        t = parsedate_tz(data)
      File "/usr/lib/python3.9/email/_parseaddr.py", line 50, in parsedate_tz
        res = _parsedate_tz(data)
      File "/usr/lib/python3.9/email/_parseaddr.py", line 72, in _parsedate_tz
        if data[0].endswith(',') or data[0].lower() in _daynames:
    IndexError: list index out of range

The fix is rather straight-forward: guard against empty lists, after
splitting on whitespace, but before accessing the first element.
(cherry picked from commit 989f6a3800)

Co-authored-by: wouter bolsterlee <wouter@bolsterl.ee>
2021-08-26 17:48:20 +02:00
..
NEWS.d bpo-45001: Make email date parsing more robust against malformed input (GH-27946) (GH-27973) 2021-08-26 17:48:20 +02:00
ACKS bpo-39091: Fix segfault when Exception constructor returns non-exception for gen.throw. (GH-17658) (GH-27573) 2021-08-03 12:10:54 +02:00
coverity_model.c bpo-35808: Retire pgen and use pgen2 to generate the parser (GH-11814) 2019-03-01 15:34:44 -08:00
gdbinit gdbinit: Use proper define syntax (GH-19557) 2020-04-23 05:49:26 -07:00
HISTORY Fix typos mostly in comments, docs and test names (GH-15209) 2019-08-30 16:21:19 -04:00
indent.pro
Porting
python-config.in bpo-38468 : Refactor python-config (#16749) 2019-10-15 11:18:47 -03:00
python-config.sh.in bpo-37925: Mention --embed in python-config usage (GH-15458) 2019-08-26 23:45:36 +02:00
python-embed.pc.in bpo-36721: Add --embed option to python-config (GH-13500) 2019-05-23 03:30:23 +02:00
python-wing3.wpr Mark files as executable that are meant as scripts. (GH-15354) 2019-09-09 07:16:33 -07:00
python-wing4.wpr Mark files as executable that are meant as scripts. (GH-15354) 2019-09-09 07:16:33 -07:00
python-wing5.wpr Mark files as executable that are meant as scripts. (GH-15354) 2019-09-09 07:16:33 -07:00
python.man bpo-41525: Make the Python program help ASCII-only (GH-21836) 2020-09-08 17:47:53 -07:00
python.pc.in bpo-36721: Add --embed option to python-config (GH-13500) 2019-05-23 03:30:23 +02:00
README
README.AIX
README.coverity
README.valgrind
requirements-test.txt bpo-40503: PEP 615: Tests and implementation for zoneinfo (GH-19909) 2020-05-16 10:20:06 +02:00
SpecialBuilds.txt bpo-39489: Remove COUNT_ALLOCS special build (GH-18259) 2020-02-03 15:17:15 +01:00
svnmap.txt
valgrind-python.supp bpo-35561: Supress valgrind false alarm on epoll_ctl(event) (GH-18060) 2020-01-19 23:38:37 +01:00
vgrindefs

README 

Python Misc subdirectory
========================

This directory contains files that wouldn't fit in elsewhere.  Some
documents are only of historic importance.

Files found here
----------------

ACKS                    Acknowledgements
gdbinit                 Handy stuff to put in your .gdbinit file, if you use gdb
HISTORY                 News from previous releases -- oldest last
indent.pro              GNU indent profile approximating my C style
NEWS                    News for this release (for some meaning of "this")
Porting                 Mini-FAQ on porting to new platforms
python-config.in        Python script template for python-config
python.man              UNIX man page for the python interpreter
python.pc.in            Package configuration info template for pkg-config
python-wing*.wpr        Wing IDE project file
README                  The file you're reading now
README.AIX              Information about using Python on AIX
README.coverity         Information about running Coverity's Prevent on Python
README.valgrind         Information for Valgrind users, see valgrind-python.supp
SpecialBuilds.txt       Describes extra symbols you can set for debug builds
svnmap.txt              Map of old SVN revs and branches to hg changeset ids,
                        help history-digging
valgrind-python.supp    Valgrind suppression file, see README.valgrind
vgrindefs               Python configuration for vgrind (a generic pretty printer)