chromium-dev/chromium-icu72-2.patch

From 103e1ff08c00590be56c98aa5647e92c7fa78631 Mon Sep 17 00:00:00 2001
From: Mustafa Emre Acer <meacer@chromium.org>
Date: Fri, 18 Nov 2022 22:52:00 +0000
Subject: [PATCH] IDN Spoof Checks: Disallow ZWJ and ZWNJ in ICU versions below
 72

ICU 72 updates to Unicode 15 which changes the zero width joiner (ZWJ)
and zero width non-joiner (ZWNJ) characters from
Identifier_Status=Allowed to Identifier_Status=Restricted. These
characters are therefore no longer allowed by default in ICU 72.

crbug/694157 recently implemented Non-Transitional IDNA 2008 behind a
flag. ZWJ and ZWNJ are disallowed in Transitional Mode but allowed in
Non-Transitional Mode, so the test cases with the Non-Transitional Mode
enabled fail in ICU 72.

This CL removes ZWJ and ZWNJ from the allowed identifiers set for
ICU versions below 72. This effectively disables these characters even
in Non-Transitional Mode.

This is a temporary fix. Once ICU 72 is rolled out, we should check if
we can use UIDNA_CHECK_CONTEXTJ and explicitly add ZWJ and ZWNJ to
the allowed sets again.

Bug: 1386204, 694157
Change-Id: I606c43b9d94fea0f2331e5aed530f633bb94517c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4038542
Reviewed-by: Frank Tang <ftang@chromium.org>
Commit-Queue: Mustafa Emre Acer <meacer@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1073605}
---
 .../spoof_checks/idn_spoof_checker.cc         |  9 ++++++
 .../idn_spoof_checker_unittest.cc             | 28 +++++++++++--------
 2 files changed, 25 insertions(+), 12 deletions(-)

Index: chromium-110.0.5481.38/components/url_formatter/spoof_checks/idn_spoof_checker.cc
===================================================================
--- chromium-110.0.5481.38.orig/components/url_formatter/spoof_checks/idn_spoof_checker.cc
+++ chromium-110.0.5481.38/components/url_formatter/spoof_checks/idn_spoof_checker.cc
@@ -722,6 +722,15 @@ void IDNSpoofChecker::SetAllowedUnicodeS
   allowed_set.remove(0x200Du);  // Zero Width Joiner
 #endif
 
+#if U_ICU_VERSION_MAJOR_NUM < 72
+  // Unicode 15 changes ZWJ and ZWNJ from allowed to restricted. Restrict them
+  // in lower versions too. This only relevant in Non-Transitional Mode as
+  // Transitional Mode maps these characters out.
+  // TODO(crbug.com/1386204): Remove these after ICU 72 is rolled out.
+  allowed_set.remove(0x200Cu);  // Zero Width Non-Joiner
+  allowed_set.remove(0x200Du);  // Zero Width Joiner
+#endif
+
   uspoof_setAllowedUnicodeSet(checker_, &allowed_set, status);
 }