[tor-bugs] #31545 [Core Tor/Tor]: CID 1452819: nul-terminated string handling, possibly spurious

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#31545: CID 1452819: nul-terminated string handling, possibly spurious
-------------------------+-------------------------------------------------
     Reporter:  teor     |      Owner:  teor
         Type:  defect   |     Status:  assigned
     Priority:  Medium   |  Milestone:  Tor: 0.4.2.x-final
    Component:  Core     |    Version:  Tor: unspecified
  Tor/Tor                |   Keywords:  042-must, memory-safety?, easy,
     Severity:  Normal   |  intro, ipv6, logging, fast-fix
Actual Points:           |  Parent ID:
       Points:  0.1      |   Reviewer:
      Sponsor:           |
  Sponsor27-must         |
-------------------------+-------------------------------------------------
 Bug introduced by #21003, copying sponsors and tags.

 {{{
 /src/feature/nodelist/describe.c: 77 in format_node_description()
 71       }
 72       if (addr32h && has_addr) {
 73         memcpy(cp, " and ", 5);
 74         cp += 5;
 75       }
 76       if (has_addr) {
    CID 1452819:    (STRING_NULL)
    Passing unterminated string "cp" to "tor_addr_to_str", which expects a
 null-terminated string.
 77         tor_addr_to_str(cp, addr, TOR_ADDR_BUF_LEN, 1);
 78       }
 79
 80       return buf;
 81     }
 82
 /src/feature/nodelist/describe.c: 70 in format_node_description()
 64         cp += 4;
 65       }
 66       if (addr32h) {
 67         struct in_addr in;
 68         in.s_addr = htonl(addr32h);
 69         tor_inet_ntoa(&in, cp, INET_NTOA_BUF_LEN);
    CID 1452819:    (STRING_NULL)
    Passing unterminated string "cp" to "strlen", which expects a null-
 terminated string.
 70         cp += strlen(cp);
 71       }
 72       if (addr32h && has_addr) {
 73         memcpy(cp, " and ", 5);
 74         cp += 5;
 75       }
 }}}

 I think the best fix for this issue is using strncpy() rather than
 memcpy().

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/31545>
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