Issues with Parallel Fuzzing

[Greg McSwagger]

After a lot of troubleshooting I got afl-fuzz to work. I am trying to get AFL-Fuzz to use every core on my multi core cpu. My master mode fuzzer (-M) is giving me the error "last new path: none yet (odd, check syntax!)". The other command works fine with no errors at all. I'm using the exact same command on each terminal beside the -S for the slave and the -M for master but other than that the commands are the same. 

[Michal Zalewski]

This... is super-unlikely. The difference between -M and -S is
cosmetic and I can't see an obvious explanation for what you're
seeing. I'd double-check the command line for typos or any other
differences.

/mz

[Greg McSwagger]

I checked and there are no typos that I can see.

[Michal Zalewski]

> I checked and there are no typos that I can see.

Can you share the -M and -S command line on the list?

Cheers,
/mz

[Greg McSwagger]

The first command is 

afl-fuzz -i afl_in -o sync_dir/fuzzer01 ./binutils/readelf -M fuzzer01 -a @@

the second command is

afl-fuzz -i afl_in -o sync_dir/fuzzer02 ./binutils/readelf -S fuzzer02 -a @@

On Tuesday, August 16, 2016 at 8:14:06 PM UTC-4, Greg McSwagger wrote:

[Michal Zalewski]

> The first command is
> afl-fuzz -i afl_in -o sync_dir/fuzzer01 ./binutils/readelf -M fuzzer01 -a @@
> the second command is
> afl-fuzz -i afl_in -o sync_dir/fuzzer02 ./binutils/readelf -S fuzzer02 -a @@

You are passing -M and -S to readelf, not to AFL. As it happens, -S is
a valid option for that utility, while -M isn't.

You are also misusing the -o flag; it should just point to a shared
sync directory.

The correct syntax would be:

afl-fuzz -i afl_in -o sync_dir -M fuzzer1 ./binutils/readelf -a @@
afl-fuzz -i afl_in -o sync_dir -S fuzzer2 ./binutils/readelf -a @@

/mz