From 44ea9278b97768ee8c5df9d247f9afd43be1ed52 Mon Sep 17 00:00:00 2001
From: Frank Tang <ftang@chromium.org>
Date: Fri, 8 Nov 2024 00:13:30 -0800
Subject: [PATCH] ICU-22962 fix int32_t overflow inside handleComputeJulianDay

test
---
 icu4c/source/i18n/calendar.cpp         |  7 ++++++-
 icu4c/source/test/intltest/caltest.cpp | 12 ++++++++++++
 icu4c/source/test/intltest/caltest.h   |  1 +
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/icu4c/source/i18n/calendar.cpp b/icu4c/source/i18n/calendar.cpp
index e713fb0195ed..c3643a986896 100644
--- a/icu4c/source/i18n/calendar.cpp
+++ b/icu4c/source/i18n/calendar.cpp
@@ -3609,7 +3609,12 @@ int32_t Calendar::handleComputeJulianDay(UCalendarDateFields bestField, UErrorCo
 #endif
                     if(julianDay+testDate > nextJulianDay) { // is it past Dec 31?  (nextJulianDay is day BEFORE year+1's  Jan 1)
                         // Fire up the calculating engines.. retry YWOY = (year-1)
-                        julianDay = handleComputeMonthStart(year-1, 0, false, status); // jd before Jan 1 of previous year
+                        int32_t prevYear;
+                        if (uprv_add32_overflow(year, -1, &prevYear)) {
+                            status = U_ILLEGAL_ARGUMENT_ERROR;
+                            return 0;
+                        }
+                        julianDay = handleComputeMonthStart(prevYear, 0, false, status); // jd before Jan 1 of previous year
                         if (U_FAILURE(status)) {
                             return 0;
                         }
diff --git a/icu4c/source/test/intltest/caltest.cpp b/icu4c/source/test/intltest/caltest.cpp
index 00485c30de6d..ca3597c3f02a 100644
--- a/icu4c/source/test/intltest/caltest.cpp
+++ b/icu4c/source/test/intltest/caltest.cpp
@@ -207,6 +207,7 @@ void CalendarTest::runIndexedTest( int32_t index, UBool exec, const char* &name,
     TESTCASE_AUTO(Test22633HebrewLargeNegativeDay);
     TESTCASE_AUTO(Test22730JapaneseOverflow);
     TESTCASE_AUTO(Test22730CopticOverflow);
+    TESTCASE_AUTO(Test22962ComputeJulianDayOverflow);
 
     TESTCASE_AUTO(TestAddOverflow);
 
@@ -5898,6 +5899,17 @@ void CalendarTest::Test22730CopticOverflow() {
     assertEquals("status return without overflow", status, U_ILLEGAL_ARGUMENT_ERROR);
 }
 
+void CalendarTest::Test22962ComputeJulianDayOverflow() {
+    UErrorCode status = U_ZERO_ERROR;
+    LocalPointer<Calendar> calendar(
+        Calendar::createInstance(Locale("nds-NL-u-ca-islamic-umalqura"), status),
+        status);
+    calendar->clear();
+    calendar->set(UCAL_YEAR, -2147483648);
+    calendar->set(UCAL_WEEK_OF_YEAR, 33816240);
+    calendar->get(UCAL_ERA, status);
+    assertEquals("status return without overflow", status, U_ILLEGAL_ARGUMENT_ERROR);
+}
 void CalendarTest::TestAddOverflow() {
     UErrorCode status = U_ZERO_ERROR;
 
diff --git a/icu4c/source/test/intltest/caltest.h b/icu4c/source/test/intltest/caltest.h
index defb40508cc9..5795a176d72a 100644
--- a/icu4c/source/test/intltest/caltest.h
+++ b/icu4c/source/test/intltest/caltest.h
@@ -348,6 +348,7 @@ class CalendarTest: public CalendarTimeZoneTest {
     void Test22633RollTwiceGetTimeOverflow();
     void Test22730JapaneseOverflow();
     void Test22730CopticOverflow();
+    void Test22962ComputeJulianDayOverflow();
 
     void Test22750Roll();