From 47b321f1fa6a5bafcc69a8bb01215773a577fedc Mon Sep 17 00:00:00 2001
From: Frank Yung-Fong Tang <ftang@google.com>
Date: Mon, 13 Feb 2023 20:38:49 +0000
Subject: [PATCH] ICU-22277 correct collation error return of uninitialized
 length value while previous code return error

See #2320
---
 icu4c/source/i18n/ucol_res.cpp         |  2 +-
 icu4c/source/test/intltest/regcoll.cpp | 21 +++++++++++++++++++++
 icu4c/source/test/intltest/regcoll.h   |  3 +++
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/icu4c/source/i18n/ucol_res.cpp b/icu4c/source/i18n/ucol_res.cpp
index a955cef0e61..9bf28db264f 100644
--- a/icu4c/source/i18n/ucol_res.cpp
+++ b/icu4c/source/i18n/ucol_res.cpp
@@ -390,7 +390,7 @@ CollationLoader::loadFromData(UErrorCode &errorCode) {
     LocalUResourceBundlePointer binary(ures_getByKey(data, "%%CollationBin", nullptr, &errorCode));
     // Note: U_MISSING_RESOURCE_ERROR --> The old code built from rules if available
     // but that created undesirable dependencies.
-    int32_t length;
+    int32_t length = 0;
     const uint8_t *inBytes = ures_getBinary(binary.getAlias(), &length, &errorCode);
     CollationDataReader::read(rootEntry->tailoring, inBytes, length, *t, errorCode);
     // Note: U_COLLATOR_VERSION_MISMATCH --> The old code built from rules if available
diff --git a/icu4c/source/test/intltest/regcoll.cpp b/icu4c/source/test/intltest/regcoll.cpp
index 5717f5bcf39..6a244ac5052 100644
--- a/icu4c/source/test/intltest/regcoll.cpp
+++ b/icu4c/source/test/intltest/regcoll.cpp
@@ -1249,6 +1249,26 @@ void CollationRegressionTest::TestBeforeWithTooStrongAfter() {
     }
 }
 
+void CollationRegressionTest::TestICU22277() {
+    IcuTestErrorCode errorCode(*this, "TestICU22277");
+    UErrorCode status = U_ZERO_ERROR;
+
+    Collator* c = Collator::createInstance("JA-u-Co-priVatE-KANa", status);
+    if(c != nullptr || U_SUCCESS(status)) {
+      errcheckln(status, "Collator should have failed with MemorySanitizer: use-of-uninitialized-value error - %s",
+                 u_errorName(status));
+      delete c;
+      return;
+    }
+    c = Collator::createInstance("hE-U-cO-pRIVate-UNihan", status);
+    if(c != nullptr || U_SUCCESS(status)) {
+      errcheckln(status, "Collator should have failed with MemorySanitizer: use-of-uninitialized-value error - %s",
+                 u_errorName(status));
+      delete c;
+      return;
+    }
+}
+
 void CollationRegressionTest::compareArray(Collator &c,
                                            const char16_t tests[][CollationRegressionTest::MAX_TOKEN_LEN],
                                            int32_t testCount)
@@ -1387,6 +1407,7 @@ void CollationRegressionTest::runIndexedTest(int32_t index, UBool exec, const ch
     TESTCASE_AUTO(TestCaseFirstCompression);
     TESTCASE_AUTO(TestTrailingComment);
     TESTCASE_AUTO(TestBeforeWithTooStrongAfter);
+    TESTCASE_AUTO(TestICU22277);
     TESTCASE_AUTO_END;
 }
 
diff --git a/icu4c/source/test/intltest/regcoll.h b/icu4c/source/test/intltest/regcoll.h
index 6a6de48a852..95735a71aa3 100644
--- a/icu4c/source/test/intltest/regcoll.h
+++ b/icu4c/source/test/intltest/regcoll.h
@@ -237,6 +237,9 @@ public:
     void TestTrailingComment();
     void TestBeforeWithTooStrongAfter();
 
+    // Test use-of-uninitialized-value
+    void TestICU22277();
+
 private:
     //------------------------------------------------------------------------
     // Internal utilities