[tor-bugs] #17799 [Core Tor/Tor]: Hash All PRNG output before use

[Tor Bug Tracker & Wiki]

#17799: Hash All PRNG output before use
-------------------------------+----------------------------------------
 Reporter:  teor               |          Owner:  nickm
     Type:  defect             |         Status:  needs_review
 Priority:  Medium             |      Milestone:  Tor: 0.2.9.x-final
Component:  Core Tor/Tor       |        Version:  Tor: unspecified
 Severity:  Normal             |     Resolution:
 Keywords:  TorCoreTeam201604  |  Actual Points:
Parent ID:                     |         Points:  small/medium-remaining
 Reviewer:  asn                |        Sponsor:
-------------------------------+----------------------------------------

Comment (by asn):

 BTW, maybe we could rename the variables `n` and `sz` in
 `shake_prng_getbytes_raw()` to something more readable? e.g.
 `total_bytes_needed` and `n_bytes_to_extract`? There was already a serious
 bug in that function so making its logic as clear as possible seems
 worthwhile.

 As another question, why do we use `mmap()` to allocate space for the
 `shake_prng_t`? Couldn't we just use `tor_malloc()` which would get
 translated to `mmap()` anyway if the requested space is big enough? Are we
 doing it so that we can pass `MAP_PRIVATE` to `mmap()` or something?

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17799#comment:40>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online