memory exhaustion in ReadMPCImage

[bestshow]

Version: ImageMagick 7.0.6-1 Q16 x86_64
#./magick identify $FILE
When identify MPC file , imagemagick will allocate memory to store the data, here is the critical code:
(Mpc.c , in function ReadMPCImage)

 image->colormap=(PixelInfo *) AcquireQuantumMemory(image->colors+1,  //856
          sizeof(*image->colormap));

The “image->colors" can be obtained from local value “options” as follow, and the options is controlled by image , in other words the “image->colors" can be read from input file.
image->colors=StringToUnsignedLong(options); //402

The function StringToUnsignedLong convert string to unsigned long type, but the return value was not checked.
Here is my policy.xml to limit memory usage,but 256MB limit can be bypassed.

...
<policy domain="resource" name="area" value="100MP"/>
<policy domain="resource" name="memory" value="256MiB”/>
...

testcase: https://github.com/bestshow/p0cs/blob/master/memory_exhaustion_in_ReadMPCImage
Credit ADLab of Venustech

[mikayla-grace]

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.

[bastien-roucaries]

This fixed by adding f19ccf2#diff-5c034a4e58a115889f4296d6ff79d84e

[nohmask]

This was assigned CVE-2017-12430.