Regression: unable to create caption with convert tool

[user21089]

After an update from Debian oldstable to Jessie, the convert command locks my CPU up at 100% and never completes (even after a long time). The caption is specified using a @ syntax that's generated by Moviepy and previously worked just fine. Specifying the caption as text works around this regression.

Steps to reproduce:

• 1. echo "test" > test.txt
  
  2. convert -background transparent -fill white -font Helvetica -size 1920x121.2 -gravity south caption:@test.txt -type truecolormatte PNG32:/tmp/tmpZzdLtm.png

Observed results:

CPU stuck at 100%

Expected results:

Process finishes after a few seconds and generates the transparent image with text in it. I also tried changing all the other parameters (font, size, gravity, etc.) and it produces the same behavior.

Running just

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convert caption:@test.txt -type truecolormatte PNG32:/tmp/tmpZzdLtm.png

Results in:

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convert: not authorized `@test.txt' @ error/property.c/InterpretImageProperties/3307.

Version

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convert -version
Version: ImageMagick 6.8.9-9 Q16 x86_64 2016-05-16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2014 ImageMagick Studio LLC
Features: DPC Modules OpenMP
Delegates: bzlib cairo djvu fftw fontconfig freetype jbig jng jpeg lcms lqr ltdl lzma openexr pangocairo png rsvg tiff wmf x xml zlib

The command is generated by the following Moviepy code:

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txt_clip = ( TextClip(fullLine,color='white',method='caption',size=(clip.size[0],clip.size[1]*0.15),font='Helvetica',align="south")
                .set_duration(4)
                .set_position(("center","bottom")) )

However, I don't consider this to be the root cause, as it worked before using the same generated syntax.

Could you fix this, and, ideally, please give me a workaround to generate captions based on a text file?

Thanks

[magick]

Check your policy.xml configuration file. Debian likely added a policy preventing the use of indirect reads in response to recent security vulnerabilitie reports (e.g. convert label:@/etc/passwd passwd.png). If you remove the '@' policy you should be able to use caption:@test.txt again.

[user21089]

Interesting! Indeed the policy.xml file in the package maintainer's version removed the rights to use the @ indirection. However, when I commented this out I had only partial success.

The following succeeds now:

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convert  -gravity south caption:@test.txt -type truecolormatte PNG32:/tmp/tmp968ZtD.png

But the following still hangs at 100%:

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convert -size 632x55 -gravity south caption:@test.txt -type truecolormatte PNG32:/tmp/tmp968ZtD.png

I also commented out all the other policies in case it was a similar issue, with no change in behavior.

Can I also request that the failure mode be changed from 100% CPU usage to an error message?

Thanks for the help so far

[magick]

Thanks for the problem report. We can reproduce it and will have a patch to fix it in GIT master branch @ https://github.com/ImageMagick/ImageMagick later today. The patch will be available in the beta releases of ImageMagick @ http://www.imagemagick.org/download/beta/ by sometime tomorrow.

[user21089]

Thanks for such quick response times! After some research I figured out how to build the latest code on my Debian system (the Debian build log from the package maintainer helped https://buildd.debian.org/status/fetch. ... 1464822354) and I confirmed that the bug is fixed!

Great work