patchThe FreeType Project - Patches: patch #8779, Add support for multiple files...

 
 

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patch #8779: Add support for multiple files when fuzzing.

Submitter:  bungeman <bungeman>
Submitted:  Fri 23 Oct 2015 04:23:10 PM UTC
   
 
Category:  None Priority:  5 - Normal
Status:  Done Privacy:  Public
Assigned to:  wl Open/Closed:  Closed

Mon 02 Nov 2015 06:24:14 AM UTC, comment #4: 

The fuzzer bot is not taking advantage of this new functionality
because it does not have the corresponding seeds.
Can one of you submit at least one seed file to git and point me at it?

Kostya Serebryany <kcc>
Group Member
Mon 02 Nov 2015 05:56:58 AM UTC, comment #3: 

I've now applied your patch, extended with some comments (which I ask you to provide in greater numbers for future contributions :-), formatted to look more like other FreeType code, and slightly modified to reduce clang warnings.

Thanks!

Werner LEMBERG <wl>
Group administrator
Mon 26 Oct 2015 07:48:48 PM UTC, comment #2: 


>> it appears that the fuzzer currently truncates inputs before calling into the mutator


Yep. Just bump up the max_len flag.

>> It would be nice if the fuzzer supported multiple independent inputs directly

Absolutely, but this is not trivial. We are still thinking on
the ways to do this.

Kostya Serebryany <kcc>
Group Member
Fri 23 Oct 2015 05:25:01 PM UTC, comment #1: 

Note that this is of somewhat limited utility, in that it appears that the fuzzer currently truncates inputs before calling into the mutator. As a result, depending on the fuzzer max_len, this only works for rather small inputs. It would be nice if the fuzzer supported multiple independent inputs directly (or if there were some 'make this input smaller' callback).

Also, this isn't the highest quality code, it could probably stand some refactoring. It was written this way mostly to keep ftfuzzer.cc stand alone and independent of ftmutator.cc (and just have ftmutator.cc depend on ftfuzzer.cc).

bungeman <bungeman>
Fri 23 Oct 2015 04:23:10 PM UTC, original submission:  

The patch attached is a start at providing the ability to fuzz multiple files. This uses tar as the storage format. On the ftfuzzer.cc side it adds code to decode tar format input, using the first contained file as the font and the rest as attachments. The ftmutator.cc file provides a custom mutator which will mutate the individual files in a tar archive if the input is readable as tar.

This does add a dependency on libarchive. This allows for fuzzing pfa/pfb with afm/pfm attachments.

bungeman <bungeman>

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

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    Follow 5 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2015-11-02 wl StatusNone Done
        Assigned toNone wl
        Open/ClosedOpen Closed
    2015-10-23 bungeman Attached File- Added 0001-Add-ftfuzzer-support-for-multi-file-fonts.patch, #35269
        Carbon-Copy- Added kcc

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