[tor-bugs] #30920 [Core Tor/Tor]: Detect uint64 overflow in config_parse_units()

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#30920: Detect uint64 overflow in config_parse_units()
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 Reporter:  nickm          |          Owner:  (none)
     Type:  defect         |         Status:  new
 Priority:  Low            |      Milestone:  Tor: 0.4.2.x-final
Component:  Core Tor/Tor   |        Version:
 Severity:  Minor          |     Resolution:
 Keywords:  easy overflow  |  Actual Points:
Parent ID:                 |         Points:
 Reviewer:                 |        Sponsor:
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Comment (by teor):

 Replying to [comment:10 guigom]:
 > First of all, sorry for the late reply
 >
 > Replying to [comment:9 nickm]:
 > > >  Is this the expected behavior, or should it fallback to UINT64_MAX?
 > >
 > > I think that's a better behavior for config_parse_memunit().  In the
 case of config_parse_memunit(), it's better that the user be told about
 the problem than to have us silently ignore their request.
 >
 > Understood, in that case is it ok to detect overflow inside
 config_parse_memunit() by check if nowrap_multiplication yielded
 UINTMAX_64? It seems quite strange in my opinion to specify such value
 explicitly.

 Maybe we should fail on anything larger than SSIZE_T_MAX?
 (SSIZE_T_MAX is half the maximum possible memory size.)

 > In addition to that I'm not sure if float multiplication should be
 handled as well or this ticket should just focus on unsigned integer.

 No, we don't have any critical code that uses float multiplication.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/30920#comment:11>
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