From 855b35e6d65079085d580ab3063637d94c8f3e0a Mon Sep 17 00:00:00 2001 From: Johannes Rudolph Date: Tue, 30 Oct 2018 13:52:29 +0100 Subject: CVE-2018-18854 Use TreeMap instead of HashMap for JsObject key/value pairs, fixes #277 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The problem is that with String's hashCode implementation it is too simple to create synthetic collisions. This allows an attacker to create an object with keys that all collide which leads to a performance drop for the HashMap just for creating the map in the first place. See https://github.com/scala/bug/issues/11203 for more information about the underlying HashMap issue. For the time being, it seems safer to use a TreeMap which uses String ordering. Benchmarks suggest that using a TreeMap is only ~6% slower for reasonably sized JSON objects up to 100 keys. Benchmark for non-colliding keys: Benchmark (_size) (parser) Mode Cnt Score Error Units ExtractFieldsBenchmark.readSpray 1 HashMap thrpt 5 1195832.262 ± 64366.605 ops/s ExtractFieldsBenchmark.readSpray 1 TreeMap thrpt 5 1342009.641 ± 17307.555 ops/s ExtractFieldsBenchmark.readSpray 10 HashMap thrpt 5 237173.327 ± 70341.742 ops/s ExtractFieldsBenchmark.readSpray 10 TreeMap thrpt 5 233510.618 ± 69638.750 ops/s ExtractFieldsBenchmark.readSpray 100 HashMap thrpt 5 23202.016 ± 1514.763 ops/s ExtractFieldsBenchmark.readSpray 100 TreeMap thrpt 5 21899.072 ± 823.225 ops/s ExtractFieldsBenchmark.readSpray 1000 HashMap thrpt 5 2073.754 ± 66.093 ops/s ExtractFieldsBenchmark.readSpray 1000 TreeMap thrpt 5 1793.329 ± 43.603 ops/s ExtractFieldsBenchmark.readSpray 10000 HashMap thrpt 5 208.160 ± 7.466 ops/s ExtractFieldsBenchmark.readSpray 10000 TreeMap thrpt 5 160.349 ± 5.809 ops/s --- src/main/scala/spray/json/JsValue.scala | 7 ++++--- src/main/scala/spray/json/JsonParser.scala | 7 ++++--- 2 files changed, 8 insertions(+), 6 deletions(-) (limited to 'src/main/scala/spray') diff --git a/src/main/scala/spray/json/JsValue.scala b/src/main/scala/spray/json/JsValue.scala index 7cd8cd8..9ed94da 100644 --- a/src/main/scala/spray/json/JsValue.scala +++ b/src/main/scala/spray/json/JsValue.scala @@ -19,6 +19,7 @@ package spray.json import collection.immutable +import scala.collection.immutable.TreeMap /** * The general type of a JSON AST node. @@ -53,10 +54,10 @@ case class JsObject(fields: Map[String, JsValue]) extends JsValue { def getFields(fieldNames: String*): immutable.Seq[JsValue] = fieldNames.toIterator.flatMap(fields.get).toList } object JsObject { - val empty = JsObject(Map.empty[String, JsValue]) - def apply(members: JsField*) = new JsObject(Map(members: _*)) + val empty = JsObject(TreeMap.empty[String, JsValue]) + def apply(members: JsField*): JsObject = new JsObject(TreeMap(members: _*)) @deprecated("Use JsObject(JsValue*) instead", "1.3.0") - def apply(members: List[JsField]) = new JsObject(Map(members: _*)) + def apply(members: List[JsField]): JsObject = apply(members: _*) } /** diff --git a/src/main/scala/spray/json/JsonParser.scala b/src/main/scala/spray/json/JsonParser.scala index 71c4c11..fb94b9c 100644 --- a/src/main/scala/spray/json/JsonParser.scala +++ b/src/main/scala/spray/json/JsonParser.scala @@ -18,9 +18,11 @@ package spray.json import scala.annotation.{switch, tailrec} import java.lang.{StringBuilder => JStringBuilder} -import java.nio.{CharBuffer, ByteBuffer} +import java.nio.{ByteBuffer, CharBuffer} import java.nio.charset.Charset +import scala.collection.immutable.TreeMap + /** * Fast, no-dependency parser for JSON as defined by http://tools.ietf.org/html/rfc4627. */ @@ -86,8 +88,7 @@ class JsonParser(input: ParserInput) { val nextMap = map.updated(key, jsValue) if (ws(',')) members(nextMap) else nextMap } - var map = Map.empty[String, JsValue] - map = members(map) + val map = members(TreeMap.empty[String, JsValue]) require('}') JsObject(map) } else { -- cgit v1.2.3