On Tue, Jun 06, 2017 at 05:56:20AM +0200, Jason A. Donenfeld wrote:
> Hey Ted,
>
> On Tue, Jun 6, 2017 at 5:00 AM, Theodore Ts'o <ty...@mit.edu> wrote:
> > Note that crypto_rng_reset() is called by big_key_init() in
> > security/keys/big_key.c as a late_initcall(). So if we are on a
> > system where the crng doesn't get initialized until during the system
> > boot scripts, and big_key is compiled directly into the kernel, the
> > boot could end up deadlocking.
> >
> > There may be other instances of where crypto_rng_reset() is called by
> > an initcall, so big_key_init() may not be an exhaustive enumeration of
> > potential problems. But this is an example of why the synchronous
> > API, although definitely much more convenient, can end up being a trap
> > for the unwary....
>
> Thanks for pointing this out. I'll look more closely into it and see
> if I can figure out a good way of approaching this.
Would it work for wait_for_random_bytes() to include a
WARN_ON(system_state < SYSTEM_RUNNING);
to catch those kinds of cases?
- Kevin
