v5.1.3

Security release. Fixes five vulnerabilities, released together in 5.2.1, 5.1.3, 5.0.9, 4.3.6 and 3.2.12: a pipelined get_multi returning another key's value (GHSA-p6pm-ch9v-44vx); unbounded retries and routing tokens that add meta flags (GHSA-4qp6-2jcr-596v); unbounded decompression and reply sizes (GHSA-3553-vcg5-72jw); per-request raw: true ignored on reads (GHSA-wr87-m4jw-29x5); and a forked child resending the parent's requests or ending its TLS session (GHSA-w39f-xq2m-4g8x). Upgrading is strongly recommended.

Security:

• Fix pipelined get_multi returning one key's value for another after an error reply (GHSA-p6pm-ch9v-44vx)
  • The pipelined reply parser took any reply without a body for the end of the batch. An error reply for one key (CLIENT_ERROR, SERVER_ERROR, or EN from a proxy) ended it early, and the replies still on the connection were read as the replies to later commands, so a get could return another key's value
  • Keys are now measured in bytes as sent, after base64 encoding when the key needs it. A key under 250 characters but over 250 bytes on the wire (for example, one with many non-ASCII characters) was the easiest way to cause that error reply. Such keys are now truncated like other long keys; keys that worked before are unchanged
  • Affects the meta protocol since 3.2.0 (the default since 5.0.0); fixed in 5.2.1, 5.1.3, 5.0.9, 4.3.6 and 3.2.12
• Reject routing tokens that add meta flags, and stop retrying an unresponsive server forever (GHSA-4qp6-2jcr-596v)
  • p_token and l_token now reject whitespace and control characters, not just CR, LF and NUL. A space let a token add meta flags to the request it was sent with: changing an item's TTL on a read, creating stub items on a miss, turning a delete into a stale tombstone, or reading a different key
  • Affects 5.1.0 and later; fixed in 5.2.1 and 5.1.3
  • A server that accepted connections but never answered (or dropped the connection on a request) was retried forever, hanging the caller, because each successful reconnect reset the failure count. Requests now fail after socket_max_failures attempts and the server is marked down, as when it can't be reached at all; it gets a full set of attempts again after down_retry_delay
  • Affects all versions; fixed in 5.2.1, 5.1.3, 5.0.9, 4.3.6 and 3.2.12
• Limit decompressed and reply value sizes (GHSA-3553-vcg5-72jw)
  • Values flagged as compressed were inflated without limit, so a small stored value could expand to gigabytes on read, whatever the client's compress or serializer settings. The new decompressed_max_bytes option (default 128 MiB; nil disables it) makes a read that would pass it raise Dalli::UnmarshalError. Custom compressors whose decompress takes only the data keep working, without the limit
  • The value size in a reply was used to read or buffer that many bytes, so a malicious server could make the client allocate gigabytes. Sizes over 1 GiB, memcached's largest item, now raise Dalli::DalliError before reading
  • Affects all versions; fixed in 5.2.1, 5.1.3, 5.0.9, 4.3.6 and 3.2.12
• Honor per-request raw: true on reads, and add Dalli::JSONSerializer (GHSA-wr87-m4jw-29x5)
  • get_multi, get_multi_cas, get_multi_with_metadata, get_cas and get_with_metadata ignored a per-request raw: true and deserialized the value according to its stored flags, so a caller who asked for raw bytes could still have Marshal.load run on data someone else wrote to memcached. They now return the stored bytes
  • The raw part affects get_with_metadata since 4.2.0, and the other methods since they gained per-request options in 5.1.0
  • serializer: JSON reads values with JSON.load, which on json gem versions before 3.0 creates an object of the class named in a stored json_class key when the json additions are loaded. The new Dalli::JSONSerializer reads with JSON.parse and only returns plain JSON types. The README and the Marshal security warning now recommend it; serializer: JSON itself is unchanged
  • The serializer: JSON part affects any version used with the json gem before 3.0
• Keep a forked child from writing to or closing the parent's connection (GHSA-w39f-xq2m-4g8x)
  • A child forked while the parent had requests buffered but not yet sent, such as quiet writes inside a quiet block, sent them again when it closed the client or reconnected: quiet writes ran twice, and the parent's later replies could be read as the replies to other requests, returning one key's value for another. Dalli now buffers requests itself and a forked child discards them
  • Affects 4.2.0 and later; fixed in 5.2.1, 5.1.3, 5.0.9 and 4.3.6
  • With TLS, a forked child that closed the client (or reconnected after detecting the fork) sent a TLS close on the connection the parent was still using, ending the parent's session. A forked child now closes only its own copy of the socket
  • Affects all versions with TLS; fixed in 5.2.1, 5.1.3, 5.0.9, 4.3.6 and 3.2.12

Bug fixes:

• An exception raised by a get_multi block (such as Timeout::Error) was treated as a network failure: swallowed, with the whole get_multi retried and keys yielded twice. It now reaches the caller