out of memory when processing this GIF

[mohanson]

source: http://lavender.b0.upaiyun.com/ex.gif

import PIL
import PIL.Image

im = PIL.Image.open('example.gif')
print(im.size)
print(im.n_frames)  # will crash

[root /tmp] python3 run.py 
(320, 240)
Killed

The problem appear on this line https://github.com/python-pillow/Pillow/blob/master/PIL/GifImagePlugin.py#L261, self.dispose_extent is very huge.

env: python3.5 on linux, free mem is 2G.

thanks.

[mohanson]

any idea?

[wiredfool]

Well, as you've noted, the dispose_extent of frame 90 is rather large:

(Pdb) self.dispose_extent
(37042, 49425, 90174, 109354)
(Pdb) frame
90

This is fed to crop, which ultimately returns a new image. Or, tries to, as that's a rather large image.

Any potential fix for #2383 could interact badly with this, as the dispose_extent winds up being the tile extents as well.

Crop should really have the DecompressionBomb warning applied, as it can increase the size of the image. But in this case, we're calling into the core image object crop, not Image.crop, so we'd need to either hoist it to a python level function or call the decompression_bomb_check from the C layer.