zulip/zerver/migrations/0360_merge_0358_0359.py

# Generated by Django 3.2.7 on 2021-10-04 17:49

from typing import Any, List

from django.db import migrations


class Migration(migrations.Migration):
    dependencies = [
        ("zerver", "0358_split_create_stream_policy"),
        ("zerver", "0359_re2_linkifiers"),
    ]

    operations: List[Any] = []
CVE-2021-41115: Use re2 for user-supplied linkifier patterns. Zulip attempts to validate that the regular expressions that admins enter for linkifiers are well-formatted, and only contain a specific subset of regex grammar. The process of checking these properties (via a regex!) can cause denial-of-service via backtracking. Furthermore, this validation itself does not prevent the creation of linkifiers which themselves cause denial-of-service when they are executed. As the validator accepts literally anything inside of a `(?P<word>...)` block, any quadratic backtracking expression can be hidden therein. Switch user-provided linkifier patterns to be matched in the Markdown processor by the `re2` library, which is guaranteed constant-time. This somewhat limits the possible features of the regular expression (notably, look-head and -behind, and back-references); however, these features had never been advertised as working in the context of linkifiers. A migration removes any existing linkifiers which would not function under re2, after printing them for posterity during the upgrade; they are unlikely to be common, and are impossible to fix automatically. The denial-of-service in the linkifier validator was discovered by @erik-krogh and @yoff, as GHSL-2021-118. 2021-09-29 01:27:54 +02:00			`# Generated by Django 3.2.7 on 2021-10-04 17:49`

			`from typing import Any, List`

			`from django.db import migrations`


			`class Migration(migrations.Migration):`
			`dependencies = [`
			`("zerver", "0358_split_create_stream_policy"),`
			`("zerver", "0359_re2_linkifiers"),`
			`]`

			`operations: List[Any] = []`