From 93a1ccabdede416425473329b8c718d507c55e29 Mon Sep 17 00:00:00 2001
From: Ronald Oussoren <ronaldoussoren@mac.com>
Date: Mon, 19 Oct 2020 20:16:21 +0200
Subject: bpo-41471: Ignore invalid prefix lengths in system proxy settings on
 macOS (GH-22762)

---
 Lib/urllib/request.py | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'Lib/urllib/request.py')

diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index 2a3d71554f..a8c870b977 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -2596,6 +2596,11 @@ def _proxy_bypass_macosx_sysconf(host, proxy_settings):
                 mask = 8 * (m.group(1).count('.') + 1)
             else:
                 mask = int(mask[1:])
+
+            if mask < 0 or mask > 32:
+                # System libraries ignore invalid prefix lengths
+                continue
+
             mask = 32 - mask
 
             if (hostIP >> mask) == (base >> mask):
-- 
cgit v1.2.1