convert:not authorized `aaaa` @ error/constitute.c/ReadImage/453

Question

I want to create a captcha pic by use convert from ImageMagick.

And I follow this, but there are some problem .

Input In my linux shell:

convert -background white -fill black -font FreeSerif-Bold -pointsize 36 label:'adfgh' ./test.png

The Error is:

convert:not authorized adfgh @ error/constitute.c/ReadImage/453. convert:missing an image filename ./test.png @ error/convert.c/ConvertImageCommand/3015

My ImageMagick: Version:6.7.2-7 , I install it with yum install ImageMagick .

I'm clueless. Any advice please?

Answer 1

Note: the solution in this and other answers involves disabling safety measures that are there to fix arbitrary code execution vulnerabilities. See for instance this ghostscript-related and this ubuntu-related announcement. Only go forward with these solutions if the input to convert comes from a trusted source.

I use ImageMagick in php (v.7.1) to slice PDF file to images.

First I got errors like:

Exception type: ImagickException

Exception message: not authorized ..... @ error/constitute.c/ReadImage/412

After some changes in /etc/ImageMagick-6/policy.xml I start getting erroes like:

Exception type: ImagickException

Exception message: unable to create temporary file ..... Permission denied @ error/pdf.c/ReadPDFImage/465

My fix:

In file /etc/ImageMagick-6/policy.xml (or /etc/ImageMagick/policy.xml)

1. comment line

   <!-- <policy domain="coder" rights="none" pattern="MVG" /> -->
   

2. change line

   <policy domain="coder" rights="none" pattern="PDF" />
   

   to

   <policy domain="coder" rights="read|write" pattern="PDF" />
   

3. add line

   <policy domain="coder" rights="read|write" pattern="LABEL" />
   

Then restart your web server (nginx, apache).

Answer 2

I use many times the ImageMagic convert command to convert *.tif files to *.pdf files.

I don't know why but today I began to receive the following error:

convert: not authorized `a.pdf' @ error/constitute.c/WriteImage/1028.

After issuing the command:

convert a.tif a.pdf

After reading the above answers I edited the file /etc/ImageMagick-6/policy.xml

and changed the line:

policy domain="coder" rights="none" pattern="PDF" 

to

policy domain="coder" rights="read|write" pattern="PDF"

and now everything works fine.

I have "ImageMagick 6.8.9-9 Q16 x86_64 2018-09-28" on "Ubuntu 16.04.5 LTS".