From fc76660f589ac07e45e9cd34ccb8087aeb11904b Mon Sep 17 00:00:00 2001
From: Sarah Boyce <42296566+sarahboyce@users.noreply.github.com>
Date: Fri, 12 Jul 2024 11:38:34 +0200
Subject: [PATCH] [4.2.x] Fixed CVE-2024-41989 -- Prevented excessive memory
 consumption in floatformat.

Thanks Elias Myllymäki for the report.

Co-authored-by: Shai Berger <shai@platonix.com>

CVE: CVE-2024-41989

Upstream-Status: Backport [https://github.com/django/django/commit/fc76660f589ac07e45e9cd34ccb8087aeb11904b]

Signed-off-by: Soumya Sambu <soumya.sambu@windriver.com>
---
 django/template/defaultfilters.py               | 13 +++++++++++++
 .../filter_tests/test_floatformat.py            | 17 +++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/django/template/defaultfilters.py b/django/template/defaultfilters.py
index a1d77f5..4884852 100644
--- a/django/template/defaultfilters.py
+++ b/django/template/defaultfilters.py
@@ -135,6 +135,19 @@ def floatformat(text, arg=-1):
     except ValueError:
         return input_val

+    _, digits, exponent = d.as_tuple()
+    try:
+        number_of_digits_and_exponent_sum = len(digits) + abs(exponent)
+    except TypeError:
+        # Exponent values can be "F", "n", "N".
+        number_of_digits_and_exponent_sum = 0
+
+    # Values with more than 200 digits, or with a large exponent, are returned "as is"
+    # to avoid high memory consumption and potential denial-of-service attacks.
+    # The cut-off of 200 is consistent with django.utils.numberformat.floatformat().
+    if number_of_digits_and_exponent_sum > 200:
+        return input_val
+
     try:
         m = int(d) - d
     except (ValueError, OverflowError, InvalidOperation):
diff --git a/tests/template_tests/filter_tests/test_floatformat.py b/tests/template_tests/filter_tests/test_floatformat.py
index cfc3eaf..bd0a998 100644
--- a/tests/template_tests/filter_tests/test_floatformat.py
+++ b/tests/template_tests/filter_tests/test_floatformat.py
@@ -55,6 +55,7 @@ class FunctionTests(SimpleTestCase):
         self.assertEqual(floatformat(1.5e-15, 20), '0.00000000000000150000')
         self.assertEqual(floatformat(1.5e-15, -20), '0.00000000000000150000')
         self.assertEqual(floatformat(1.00000000000000015, 16), '1.0000000000000002')
+        self.assertEqual(floatformat("1e199"), "1" + "0" * 199)

     def test_zero_values(self):
         self.assertEqual(floatformat(0, 6), '0.000000')
@@ -68,6 +69,22 @@ class FunctionTests(SimpleTestCase):
         self.assertEqual(floatformat(pos_inf), 'inf')
         self.assertEqual(floatformat(neg_inf), '-inf')
         self.assertEqual(floatformat(pos_inf / pos_inf), 'nan')
+        self.assertEqual(floatformat("inf"), "inf")
+        self.assertEqual(floatformat("NaN"), "NaN")
+
+    def test_too_many_digits_to_render(self):
+        cases = [
+            "1e200",
+            "1E200",
+            "1E10000000000000000",
+            "-1E10000000000000000",
+            "1e10000000000000000",
+            "-1e10000000000000000",
+            "1" + "0" * 1_000_000,
+        ]
+        for value in cases:
+            with self.subTest(value=value):
+                self.assertEqual(floatformat(value), value)

     def test_float_dunder_method(self):
         class FloatWrapper:
--
2.40.0
