Created attachment 128227 [details] [review]
My proposed patch

libXpm does not properly handle EOF conditions when xpmGetC is called
multiple times in a row to construct a string. Instead of checking
its return value for EOF, the result is automatically casted into a
char and attached to a string.

By carefully crafting the color table in an XPM file, it is possible to
send a libXpm program like gimp into a very long lasting loop and
massive memory allocations.

Otherwise no memory issues arise, therefore this is just a purely
functional patch to dismiss invalid input.