[tor-bugs] #27730 [Core Tor/Tor]: CID 1439330: "st.st_size > 9223372036854775807L" is always false

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#27730: CID 1439330: "st.st_size > 9223372036854775807L" is always false
------------------------------+--------------------------------
     Reporter:  teor          |      Owner:  (none)
         Type:  defect        |     Status:  assigned
     Priority:  Medium        |  Milestone:  Tor: 0.3.5.x-final
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:  coverity
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:                |
------------------------------+--------------------------------
 Coverity claims:
 {{{
 *** CID 1439330:  Integer handling issues  (CONSTANT_EXPRESSION_RESULT)
 /src/lib/crypt_ops/crypto_rsa.c: 554 in
 crypto_pk_read_private_key_from_filename()
 548                                              const char *keyfile)
 549     {
 550       struct stat st;
 551       char *buf = read_file_to_str(keyfile, 0, &st);
 552       if (!buf)
 553         return -1;
    CID 1439330:  Integer handling issues  (CONSTANT_EXPRESSION_RESULT)
    "st.st_size > 9223372036854775807L" is always false regardless of the
 values of its operands. This occurs as the logical operand of "if".
 554       if (st.st_size > SSIZE_MAX)
 555         return -1;
 556
 557       int rv = crypto_pk_read_private_key_from_string(env, buf,
 558
 (ssize_t)st.st_size);
 559       memwipe(buf, 0, (size_t)st.st_size);
 }}}

 But st_size is off_t, and the POSIX standard doesn't require a particular
 size for off_t:
 {{{
 blkcnt_t and off_t shall be signed integer types.
 }}}
 http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_types.h.html#tag_13_67

 In particular, some 32-bit pointer (SSIZE_MAX) operating systems may have
 a 64-bit file off_t. (I know that at least one BSD does, and I suspect
 that macOS and Linux also do in their 64-bit file size modes.)

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/27730>
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