Thumbnailer fails with requested width=0 or height=0

[dklimpel]

Description

If you request a thumbnail with width=0&height=0 (for both scale and crop)

• container image returns HTTP 500
• Ubuntu package returns the image

I cannot explain why the platforms behave differently.
In any case, validation of the rest API is missing (#13147).

Steps to reproduce

Ubuntu package deployment

• request an thumbnail image (eg. profile image)
  • HTTP GET https://example.com/_matrix/media/r0/thumbnail/example.com/<media_id>?width=0&height=0&method=scale
  • you get the image

container deployment

• request an thumbnail image (eg. profile image)
  • HTTP GET https://example.com/_matrix/media/r0/thumbnail/example.com/<media_id>?width=0&height=0&method=scale
  • you get an error HTTP 500: {"errcode":"M_UNKNOWN","error":"Internal server error"}

2022-11-29 09:40:59,762 - synapse.http.server - 124 - ERROR - GET-13- Failed handle request via 'ThumbnailResource': <XForwardedForRequest at 0x7f46681b7220 method='GET' uri='/_matrix/media/r0/thumbnail/k8s.azure.kird.net/qQlsITBVkgBeIrbvLpbByOOy?width=0&height=0&method=scale' clientproto='HTTP/1.1' site='8083'>
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/synapse/http/server.py", line 307, in _async_render_wrapper
    callback_return = await self._async_render(request)
  File "/usr/local/lib/python3.9/site-packages/synapse/http/server.py", line 337, in _async_render
    callback_return = await raw_callback_return
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnail_resource.py", line 76, in _async_render_GET
    await self._select_or_generate_local_thumbnail(
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnail_resource.py", line 178, in _select_or_generate_local_thumbnail
    file_path = await self.media_repo.generate_local_exact_thumbnail(
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/media_repository.py", line 592, in generate_local_exact_thumbnail
    t_byte_source = await defer_to_thread(-packages/synapse/rest/media/v1/thumbnail_resource.py", line 178, in _select_or_generate_local_thumbnail
    file_path = await self.media_repo.generate_local_exact_thumbnail(
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/media_repository.py", line 592, in generate_local_exact_thumbnail
    t_byte_source = await defer_to_thread(
  File "/usr/local/lib/python3.9/site-packages/twisted/python/threadpool.py", line 244, in inContext
    result = inContext.theWork()  # type: ignore[attr-de
  File "/usr/local/lib/python3.9/site-packages/twisted/python/threadpool.py", line 244, in inContext
    result = inContext.theWork()  # type: ignore[attr-defined]
  File "/usr/local/lib/python3.9/site-packages/twisted/python/threadpool.py", line 260, in <lambda>
    inContext.theWork = lambda: context.call(  # type: ignore[attr-defined]
  File "/usr/local/lib/python3.9/site-packages/twisted/python/context.py", line 117, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/usr/local/lib/python3.9/site-packages/twisted/python/context.py", line 82, in callWithContext
    return func(*args, **kw)
  File "/usr/local/lib/python3.9/site-packages/synapse/logging/context.py", line 970, in g
    return f(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/media_repository.py", line 562, in _generate_thumbnail
    return thumbnailer.scale(t_width, t_height, t_type)
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnailer.py", line 143, in scale
    with self._resize(width, height) as scaled:
  File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnailer.py", line 135, in _resize
    return self.image.resize((width, height), Image.ANTIALIAS)
  File "/usr/local/lib/python3.9/site-packages/PIL/Image.py", line 2115, in resize
    return self._new(self.im.resize(size, resample, box))
ValueError: height and width must be > 0

I am did the same image for both plattforms / servers.

Homeserver

another homeserver

Synapse Version

various

Installation Method

Other (please mention below)

Database

single PostgreSQL server

Workers

Multiple workers

Platform

• Container / K8s platform:
  • Synapse v1.64.0 and 1.72.0 (matrixdotorg/synapse:latest)
• Debian/Ubuntu platform
  • Synapse v1.71.0 (matrix.org package)

Configuration

No response

Relevant log output

see above

Anything else that would be useful to know?

container version:

cat /usr/local/lib/python3.9/site-packages/PIL/_version.py 
# Master version for Pillow
__version__ = "9.3.0

package version:

cat /opt/venvs/matrix-synapse/lib/python3.8/site-packages/PIL/_version.py 
# Master version for Pillow
__version__ = "9.2.0"

[clokep]

Similar error stack to #10721, but slightly different input. See also the fix for that: #11288.

[feroom]

Similar error 💯

Debian/Ubuntu platform
Synapse v1.72.0 (matrix.org package)

I think this error is caused by the Element IOS client. I'm not sure, but an error appeared in the logs when an avatar was added from such clients.

[FlyveHest]

I've got many IOS clients connected to my homeserver, and the log is full of these errors. (And have been for a long time)

Also running Synapse in a container.

[FlyveHest]

Did a little more digging, this example line from my reverse proxy

x.x.x.x - - [15/Dec/2022:09:34:16 +0100] "GET /_matrix/media/r0/thumbnail/matrix-server.example/rAgGyDiZgIGXzumIIYcQhWPB?width=0&height=0&method=scale HTTP/1.1" 500 5701 "-" "Element/1.9.13 (iPhone 14 Pro Max; iOS 16.2; Scale/3.00)"

results in this in the synapse log

x/media/r0/thumbnail/matrix.gladblad.dk/rAgGyDiZgIGXzumIIYcQhWPB?width=0&height=0&method=scale' clientproto='HTTP/1.1' site='8008'>
Dec 15 09:34:16 matrix docker/synapse[1641]: Traceback (most recent call last):
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/synapse/http/server.py", line 307, in _async_render_wrapper
Dec 15 09:34:16 matrix docker/synapse[1641]:     callback_return = await self._async_render(request)
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/synapse/http/server.py", line 337, in _async_render
Dec 15 09:34:16 matrix docker/synapse[1641]:     callback_return = await raw_callback_return
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnail_resource.py", line 76, in _async_render_GET
Dec 15 09:34:16 matrix docker/synapse[1641]:     await self._select_or_generate_local_thumbnail(
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnail_resource.py", line 178, in _select_or_generate_local_thumbnail
Dec 15 09:34:16 matrix docker/synapse[1641]:     file_path = await self.media_repo.generate_local_exact_thumbnail(
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/media_repository.py", line 592, in generate_local_exact_thumbnail
Dec 15 09:34:16 matrix docker/synapse[1641]:     t_byte_source = await defer_to_thread(
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/twisted/python/threadpool.py", line 244, in inContext
Dec 15 09:34:16 matrix docker/synapse[1641]:     result = inContext.theWork()  # type: ignore[attr-defined]
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/twisted/python/threadpool.py", line 260, in <lambda>
Dec 15 09:34:16 matrix docker/synapse[1641]:     inContext.theWork = lambda: context.call(  # type: ignore[attr-defined]
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/twisted/python/context.py", line 117, in callWithContext
Dec 15 09:34:16 matrix docker/synapse[1641]:     return self.currentContext().callWithContext(ctx, func, *args, **kw)
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/twisted/python/context.py", line 82, in callWithContext
Dec 15 09:34:16 matrix docker/synapse[1641]:     return func(*args, **kw)
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/synapse/logging/context.py", line 969, in g
Dec 15 09:34:16 matrix docker/synapse[1641]:     return f(*args, **kwargs)
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/media_repository.py", line 562, in _generate_thumbnail
Dec 15 09:34:16 matrix docker/synapse[1641]:     return thumbnailer.scale(t_width, t_height, t_type)
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnailer.py", line 143, in scale
Dec 15 09:34:16 matrix docker/synapse[1641]:     with self._resize(width, height) as scaled:
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/synapse/rest/media/v1/thumbnailer.py", line 135, in _resize
Dec 15 09:34:16 matrix docker/synapse[1641]:     return self.image.resize((width, height), Image.ANTIALIAS)
Dec 15 09:34:16 matrix docker/synapse[1641]:   File "/usr/local/lib/python3.9/site-packages/PIL/Image.py", line 2115, in resize
Dec 15 09:34:16 matrix docker/synapse[1641]:     return self._new(self.im.resize(size, resample, box))
Dec 15 09:34:16 matrix docker/synapse[1641]: ValueError: height and width must be > 0

There are many many lines like this, and they all come from a various combination of IOS element clients, so maybe it would make sense to make a bugreport there as well.

But, this should probably be handled in Synapse as well.