From 42d67347988a9d09b940d550f1ffa32a8d7e43b2 Mon Sep 17 00:00:00 2001
From: Lumir Balhar <lbalhar@redhat.com>
Date: Fri, 12 Mar 2021 16:04:15 +0100
Subject: [PATCH] CVE-2020-28493

---
 jinja2/utils.py | 94 +++++++++++++++++++++++++++++--------------------
 1 file changed, 56 insertions(+), 38 deletions(-)

diff --git a/jinja2/utils.py b/jinja2/utils.py
index db9c5d0..6ab77f7 100644
--- a/jinja2/utils.py
+++ b/jinja2/utils.py
@@ -12,24 +12,12 @@ import re
 import json
 import errno
 from collections import deque
+from string import ascii_letters as _letters
+from string import digits as _digits
 from threading import Lock
 from jinja2._compat import text_type, string_types, implements_iterator, \
      url_quote, abc
 
-
-_word_split_re = re.compile(r'(\s+)')
-_punctuation_re = re.compile(
-    '^(?P<lead>(?:%s)*)(?P<middle>.*?)(?P<trail>(?:%s)*)$' % (
-        '|'.join(map(re.escape, ('(', '<', '&lt;'))),
-        '|'.join(map(re.escape, ('.', ',', ')', '>', '\n', '&gt;')))
-    )
-)
-_simple_email_re = re.compile(r'^\S+@[a-zA-Z0-9._-]+\.[a-zA-Z0-9._-]+$')
-_striptags_re = re.compile(r'(<!--.*?-->|<[^>]*>)')
-_entity_re = re.compile(r'&([^;]+);')
-_letters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
-_digits = '0123456789'
-
 # special singleton representing missing values for the runtime
 missing = type('MissingType', (), {'__repr__': lambda x: 'missing'})()
 
@@ -203,35 +191,65 @@ def urlize(text, trim_url_limit=None, rel=None, target=None):
     trim_url = lambda x, limit=trim_url_limit: limit is not None \
                          and (x[:limit] + (len(x) >=limit and '...'
                          or '')) or x
-    words = _word_split_re.split(text_type(escape(text)))
+    words = re.split(r"(\s+)", text_type(escape(text)))
     rel_attr = rel and ' rel="%s"' % text_type(escape(rel)) or ''
     target_attr = target and ' target="%s"' % escape(target) or ''
 
     for i, word in enumerate(words):
-        match = _punctuation_re.match(word)
+        head, middle, tail = "", word, ""
+        match = re.match(r"^([(<]|&lt;)+", middle)
+
         if match:
-            lead, middle, trail = match.groups()
-            if middle.startswith('www.') or (
-                '@' not in middle and
-                not middle.startswith('http://') and
-                not middle.startswith('https://') and
-                len(middle) > 0 and
-                middle[0] in _letters + _digits and (
-                    middle.endswith('.org') or
-                    middle.endswith('.net') or
-                    middle.endswith('.com')
-                )):
-                middle = '<a href="http://%s"%s%s>%s</a>' % (middle,
-                    rel_attr, target_attr, trim_url(middle))
-            if middle.startswith('http://') or \
-               middle.startswith('https://'):
-                middle = '<a href="%s"%s%s>%s</a>' % (middle,
-                    rel_attr, target_attr, trim_url(middle))
-            if '@' in middle and not middle.startswith('www.') and \
-               not ':' in middle and _simple_email_re.match(middle):
-                middle = '<a href="mailto:%s">%s</a>' % (middle, middle)
-            if lead + middle + trail != word:
-                words[i] = lead + middle + trail
+            head = match.group()
+            middle = middle[match.end() :]
+
+        # Unlike lead, which is anchored to the start of the string,
+        # need to check that the string ends with any of the characters
+        # before trying to match all of them, to avoid backtracking.
+        if middle.endswith((")", ">", ".", ",", "\n", "&gt;")):
+            match = re.search(r"([)>.,\n]|&gt;)+$", middle)
+
+            if match:
+                tail = match.group()
+                middle = middle[: match.start()]
+
+        if middle.startswith("www.") or (
+            "@" not in middle
+            and not middle.startswith("http://")
+            and not middle.startswith("https://")
+            and len(middle) > 0
+            and middle[0] in _letters + _digits
+            and (
+                middle.endswith(".org")
+                or middle.endswith(".net")
+                or middle.endswith(".com")
+            )
+        ):
+            middle = '<a href="http://%s"%s%s>%s</a>' % (
+                middle,
+                rel_attr,
+                target_attr,
+                trim_url(middle),
+            )
+
+        if middle.startswith("http://") or middle.startswith("https://"):
+            middle = '<a href="%s"%s%s>%s</a>' % (
+                middle,
+                rel_attr,
+                target_attr,
+                trim_url(middle),
+            )
+
+        if (
+            "@" in middle
+            and not middle.startswith("www.")
+            and ":" not in middle
+            and re.match(r"^\S@\w[\w.-]*\.\w$", middle)
+        ):
+            middle = '<a href="mailto:%s">%s</a>' % (middle, middle)
+
+        words[i] = head + middle + tail
+
     return u''.join(words)
 
 
-- 
2.29.2