id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
37292	TemporaryUploadedFile raises OSError for a filename with a very long extension	Prakhar Pratyush		"Uploading a file whose extension is long enough makes the request die with an unhandled `OSError` instead of the name being sanitized.

`TemporaryUploadedFile` takes the extension straight off the client-supplied filename and uses it as the suffix of the temporary file:

{{{
    _, ext = os.path.splitext(name)
    file = tempfile.NamedTemporaryFile(
        suffix="".upload"" + ext, dir=settings.FILE_UPLOAD_TEMP_DIR
    )
    super().__init__(file, name, content_type, size, charset, content_type_extra)
}}}

`NAME_MAX` is 255 bytes on ext4 and most other filesystems, and `tempfile` adds ""tmp"" plus 8 random characters on top of the 7-byte "".upload"", so an extension of 238 bytes or more is enough to make `os.open()` fail.

=== Replication

{{{
>>> from django.core.files.uploadedfile import TemporaryUploadedFile
>>> TemporaryUploadedFile(""x."" + ""a"" * 250, ""text/plain"", 6, None)
Traceback (most recent call last):
  File ""<stdin>"", line 1, in <module>
  File ""/srv/zulip/.venv/lib/python3.10/site-packages/django/core/files/uploadedfile.py"", line 77, in __init__
    file = tempfile.NamedTemporaryFile(
  File ""/usr/lib/python3.10/tempfile.py"", line 714, in NamedTemporaryFile
    file = _io.open(dir, mode, buffering=buffering,
  File ""/usr/lib/python3.10/tempfile.py"", line 711, in opener
    fd, name = _mkstemp_inner(dir, prefix, suffix, flags, output_type)
  File ""/usr/lib/python3.10/tempfile.py"", line 395, in _mkstemp_inner
    fd = _os.open(file, flags, 0o600)
OSError: [Errno 36] File name too long: '/tmp/tmpm5gby_up.upload.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'
}}}

**Also**:

Over a real request you need an upload larger than `FILE_UPLOAD_MAX_MEMORY_SIZE` so that `MemoryFileUploadHandler` declines it and the temporary file handler takes over. Anything that reads `request.POST` on that request will then raise, it comes out as a 500."	Bug	new	File uploads/storage	5.2	Normal			Prakhar Pratyush	Unreviewed	0	0	0	0	0	0