Tor is out (security patches)

Roger Dingledine arma at
Wed Jan 19 03:11:57 UTC 2011

Tor includes all the patches from Tor, which
continues our recent code security audit work. The main fix resolves
a remote heap overflow vulnerability that can allow remote code
execution (CVE-2011-0427). Other fixes address a variety of assert
and crash bugs, most of which we think are hard to exploit remotely.

All Tor users should upgrade.

Changes in version - 2011-01-15
  o Major bugfixes (security), also included in
    - Fix a heap overflow bug where an adversary could cause heap
      corruption. This bug probably allows remote code execution
      attacks. Reported by "debuger". Fixes CVE-2011-0427. Bugfix on
    - Prevent a denial-of-service attack by disallowing any
      zlib-compressed data whose compression factor is implausibly
      high. Fixes part of bug 2324; reported by "doorss".
    - Zero out a few more keys in memory before freeing them. Fixes
      bug 2384 and part of bug 2385. These key instances found by
      "cypherpunks", based on Andrew Case's report about being able
      to find sensitive data in Tor's memory space if you have enough
      permissions. Bugfix on 0.0.2pre9.

  o Major bugfixes (crashes), also included in
    - Prevent calls to Libevent from inside Libevent log handlers.
      This had potential to cause a nasty set of crashes, especially
      if running Libevent with debug logging enabled, and running
      Tor with a controller watching for low-severity log messages.
      Bugfix on Fixes bug 2190.
    - Add a check for SIZE_T_MAX to tor_realloc() to try to avoid
      underflow errors there too. Fixes the other part of bug 2324.
    - Fix a bug where we would assert if we ever had a file (or another file read directly into
      memory) of exactly SIZE_T_CEILING bytes. Fixes bug 2326; bugfix
      on Found by doorss.
    - Fix some potential asserts and parsing issues with grossly
      malformed router caches. Fixes bug 2352; bugfix on Tor
      Found by doorss.

  o Minor bugfixes (other), also included in
    - Fix a bug with handling misformed replies to reverse DNS lookup
      requests in DNSPort. Bugfix on Tor Related to a
      bug reported by doorss.
    - Fix compilation on mingw when a pthreads compatibility library
      has been installed. (We don't want to use it, so we shouldn't
      be including pthread.h.) Fixes bug 2313; bugfix on
    - Fix a bug where we would declare that we had run out of virtual
      addresses when the address space was only half-exhausted. Bugfix
    - Correctly handle the case where AutomapHostsOnResolve is set but
      no virtual addresses are available. Fixes bug 2328; bugfix on Bug found by doorss.
    - Correctly handle wrapping around when we run out of virtual
      address space. Found by cypherpunks; bugfix on

  o Minor features, also included in
    - Update to the January 1 2011 Maxmind GeoLite Country database.
    - Introduce output size checks on all of our decryption functions.

  o Build changes, also included in
    - Tor does not build packages correctly with Automake 1.6 and earlier;
      added a check to to make sure that we're building with
      Automake 1.7 or later.
    - The tarball was missing src/common/OpenBSD_malloc_Linux.c
      because we built it with a too-old version of automake. Thus that
      release broke ./configure --enable-openbsd-malloc, which is popular
      among really fast exit relays on Linux.

  o Major bugfixes, new in
    - Prevent crash/heap corruption when the cbtnummodes consensus
      parameter is set to 0 or large values. Fixes bug 2317; bugfix

  o Major features, new in
    - Introduce minimum/maximum values that clients will believe
      from the consensus. Now we'll have a better chance to avoid crashes
      or worse when a consensus param has a weird value.

  o Minor features, new in
    - Make sure to disable DirPort if running as a bridge. DirPorts aren't
      used on bridges, and it makes bridge scanning somewhat easier.
    - If writing the state file to disk fails, wait up to an hour before
      retrying again, rather than trying again each second. Fixes bug
      2346; bugfix on Tor
    - Make Libevent log messages get delivered to controllers later,
      and not from inside the Libevent log handler. This prevents unsafe
      reentrant Libevent calls while still letting the log messages
      get through.
    - Detect platforms that brokenly use a signed size_t, and refuse to
      build there. Found and analyzed by doorss and rransom.
    - Fix a bunch of compile warnings revealed by mingw with gcc 4.5.
      Resolves bug 2314.

  o Minor bugfixes, new in
    - Handle SOCKS messages longer than 128 bytes long correctly, rather
      than waiting forever for them to finish. Fixes bug 2330; bugfix
      on Found by doorss.
    - Add assertions to check for overflow in arguments to
      base32_encode() and base32_decode(); fix a signed-unsigned
      comparison there too. These bugs are not actually reachable in Tor,
      but it's good to prevent future errors too. Found by doorss.
    - Correctly detect failures to create DNS requests when using Libevent
      versions before v2. (Before Libevent 2, we used our own evdns
      implementation. Its return values for Libevent's evdns_resolve_*()
      functions are not consistent with those from Libevent.) Fixes bug
      2363; bugfix on Found by "lodger".

  o Documentation, new in
    - Document the default socks host and port ( for

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