search

spray / spray-json

A lightweight, clean and simple JSON implementation in Scala
Apache License 2.0
972 stars 190 forks source link

CVE-2018-18854 Use TreeMap instead of HashMap for JsObject key/value pairs, fixes #277 #280

Closed jrudolph closed 5 years ago

jrudolph commented 5 years ago

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

/cc @plokhotnyuk

ignasi35 commented 5 years ago

LGTM