[tor-bugs] #14142 [Tor]: A 2-letter torrc file containing "Vi" causes tor to crash

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#14142: A 2-letter torrc file containing "Vi" causes tor to crash
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 Reporter:  teor    |          Owner:
     Type:  defect  |         Status:  new
 Priority:  normal  |      Milestone:  Tor: 0.2.7.x-final
Component:  Tor     |        Version:  Tor: 0.2.6.2-alpha
 Keywords:  easy    |  Actual Points:
Parent ID:          |         Points:
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 The parsing of the `VirtualAddrNetworkIPv[46]` options crashes when the
 line or file ends after the option itself. (The IPv4? option can be
 abbreviated to "Vi").

 This is an easy fix that involves checking for the empty string early on,
 before we assert on it in the parsing code.

 Discovered using afl-fuzz with a custom tor binary that parses a torrc
 file from standard input (and doesn't do much else). This kind of fuzzing
 would be easier to conduct using a test harness, rather than using the
 entire tor binary.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/14142>
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