The potential security vulnerability for the flag pre_dispatch in Parallel() class due to the eval() statement.

As the title shows, if you try to enter a statement in the flag pre_dispatch, it will run whatever you want to run. This should present a potential security vulnerability.

def f():
    return 1
p = Parallel(n_jobs=3, pre_dispatch="sys.exit(0)")
p(delayed(f)() for i in range(10)) # this will cause the system to exit

https://github.com/joblib/joblib/blob/53a8173d8e23ae8d6152fc3ee7e4962ae79e1642/joblib/parallel.py#L1020

[adrinjalali]

This fix was more about arbitrary code execution rather than an exception free run. I think 1/0 should raise an exception.

[ogrisel]

I would be ok to accept a callable if needed.