ImageMagick maybe broken by libgs9 upgrade

[Ken Brown]

On 6/24/2020 1:30 AM, Marco Atzeri via Cygwin wrote:
> On 23.06.2020 23:02, Marco Atzeri wrote:
>> On 23.06.2020 22:56, Ken Brown via Cygwin wrote:
>>>
>>> I think I've found the problem, although it will take patching and rebuilding 
>>> ImageMagick (which I haven't done) to confirm that I'm right.
>>>
>>> In the ImageMagick source file coders/ps.c:237, there's a call to 
>>> ghost_info->new_instance, a.k.a. gsapi_new_instance (see line 214). The 
>>> documentation of the latter in the ghostscript sources (psi/iapi.c:57) says 
>>> that the first argument pinstance should satisfy *pinstance == NULL in the 
>>> first call to that function.
>>>
>>> But *pinstance in this call is the variable 'interpreter', defined without 
>>> initialization in ps.c:191.  As a result, **pinstance contains garbage, and 
>>> the program eventually crashes when it tries to dereference a garbage pointer.
>>>
>>> The fix, if I'm right, is to initialize interpreter to NULL in ps.c:191.
>>>
>>> Ken
>>
>> Noted.
>>
>> Regards
>> MArco
>>
> 
> a test ImageMagick-6.9.10.11-3 is going up.
> Let me know if it solves the problem

That fixes it for my .eps file.  I didn't think of it before, but a similar 
patch to coders/pdf.c:201 will be needed for .pdf files.  I won't be able to 
test that because I haven't found a .pdf file that exhibits the problem.

Ken

Ken