[tor-bugs] #19130 [Core Tor/Tor]: Seg fault in round_int64_to_next_multiple_of()

[Tor Bug Tracker & Wiki]

#19130: Seg fault in round_int64_to_next_multiple_of()
--------------------------+--------------------------------
 Reporter:  arma          |          Owner:
     Type:  defect        |         Status:  needs_revision
 Priority:  Medium        |      Milestone:
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:                |  Actual Points:
Parent ID:                |         Points:
 Reviewer:  teor          |        Sponsor:
--------------------------+--------------------------------
Changes (by teor):

 * status:  needs_review => needs_revision
 * reviewer:   => teor


Comment:

 `number - 1` can underflow if `number` is `INT64_MIN`.
 So we need to skip the overflow check in that case.

 How about:
 {{{
 if (number > INT64_MIN)
   if (INT64_MAX - divisor < number - 1)
     return INT64_MAX;
 }}}

 Otherwise this looks good, and yes, it would be sensible to explicitly
 handle overflow and underflow, rather than leaving it to the whims of
 compilers.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19130#comment:6>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online