#30252: ImageField's to_python() stores reference to closed Image object
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Reporter: Felix Dreissig | Owner: nobody
Type: Bug | Status: new
Component: File uploads/storage | Version: 2.1
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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In django.forms.fields.ImageField's `to_python()` method, an uploaded
image is validated by `open()`ing a PIL.Image object from it and calling
`verify()` on that. Afterwards, the Image object is saved to an `image`
attribute of the uploaded file (i.e. an InMemoryUploadedFile). According
to a comment in the source, this happens so that "subclasses can reuse it
for their own validation".
Pillow closes an Image after `verify()`ing and the docs
[https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.verify
state] that it cannot be used after calling `verify` on it:
If you need to load the image after using this method, you must reopen
the image file.
For me, this resulted in the following error when trying to explicitly
call `save()` on the Image, but similar effects will probably happen for
any operation:
{{{
File ".../lib/python3.6/site-packages/PIL/Image.py", line 1960, in save
self.load()
File ".../lib/python3.6/site-packages/PIL/ImageFile.py", line 165, in
load
seek = self.fp.seek
AttributeError: 'NoneType' object has no attribute 'seek'
}}}
This could be related to #13750, but I don't think so.
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Ticket URL: <https://code.djangoproject.com/ticket/30252>
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