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 <tytso@xxxxxxx> 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