ICU-23256 Fix floating exception while divided by 0

FrankYFTang · mihnita · commit 910bb20d66f1 · 2026-03-03T15:38:59.000-08:00
See #3769
diff --git a/icu4c/source/i18n/nfrule.cpp b/icu4c/source/i18n/nfrule.cpp
@@ -158,12 +158,17 @@ NFRule::makeRules(UnicodeString& description,
         UnicodeString sbuf;
         int32_t orElseOp = description.indexOf(gVerticalLine);
 
+        uint64_t mod = util64_pow(rule1->radix, rule1->exponent);
         // we'll actually only split the rule into two rules if its
         // base value is an even multiple of its divisor (or it's one
         // of the special rules)
+        if (rule1->baseValue > 0 && rule1->radix != 0 && mod == 0) {
+            status = U_NUMBER_ARG_OUTOFBOUNDS_ERROR;
+            return;
+        }
         if ((rule1->baseValue > 0
             && (rule1->radix != 0) // ICU-23109 Ensure next line won't "% 0"
-            && (rule1->baseValue % util64_pow(rule1->radix, rule1->exponent)) == 0)
+            && (rule1->baseValue % mod == 0))
             || rule1->getType() == kImproperFractionRule
             || rule1->getType() == kDefaultRule) {
 
diff --git a/icu4c/source/test/intltest/itrbnf.cpp b/icu4c/source/test/intltest/itrbnf.cpp
@@ -86,6 +86,7 @@ void IntlTestRBNF::runIndexedTest(int32_t index, UBool exec, const char* &name,
         TESTCASE(34, testOmissionReplacementWithPluralRules);
         TESTCASE(35, TestNullDereferenceWRITE23149);
         TESTCASE(36, TestNullDereferenceREAD23184);
+        TESTCASE(39, TestDividedByZero);
 #else
         TESTCASE(0, TestRBNFDisabled);
 #endif
@@ -2781,6 +2782,14 @@ IntlTestRBNF::TestNullDereferenceREAD23184() {
     }
 }
 
+void
+IntlTestRBNF::TestDividedByZero() {
+    UParseError perror;
+    UErrorCode status = U_ZERO_ERROR;
+    RuleBasedNumberFormat rbnf(u"7060920374060940374/4:[]", Locale::getUS(), perror, status);
+    assertEquals("base is too large", U_NUMBER_ARG_OUTOFBOUNDS_ERROR, status);
+}
+
 /* U_HAVE_RBNF */
 #else
 
diff --git a/icu4c/source/test/intltest/itrbnf.h b/icu4c/source/test/intltest/itrbnf.h
@@ -167,6 +167,7 @@ class IntlTestRBNF : public IntlTest {
     void testOmissionReplacementWithPluralRules();
     void TestNullDereferenceWRITE23149();
     void TestNullDereferenceREAD23184();
+    void TestDividedByZero();
 
 protected:
     virtual void doTest(RuleBasedNumberFormat* formatter, const char* const testData[][2], UBool testParsing);
diff --git a/icu4j/main/core/src/main/java/com/ibm/icu/text/NFRule.java b/icu4j/main/core/src/main/java/com/ibm/icu/text/NFRule.java
@@ -164,14 +164,16 @@ public static void makeRules(String                description,
             StringBuilder sbuf = new StringBuilder();
             int orElseOp = description.indexOf('|');
 
+            long mod = power(rule1.radix, rule1.exponent);
+            if (rule1.baseValue > 0 && mod == 0) {
+                throw new IllegalArgumentException("value out of range");
+            }
             // we'll actually only split the rule into two rules if its
             // base value is an even multiple of its divisor (or it's one
             // of the special rules)
-            if ((rule1.baseValue > 0
-                 && rule1.baseValue % (power(rule1.radix, rule1.exponent)) == 0)
-                || rule1.baseValue == IMPROPER_FRACTION_RULE
-                || rule1.baseValue == DEFAULT_RULE)
-            {
+            if ((rule1.baseValue > 0 && rule1.baseValue % mod == 0)
+                    || rule1.baseValue == IMPROPER_FRACTION_RULE
+                    || rule1.baseValue == DEFAULT_RULE) {
 
                 // if it passes that test, new up the second rule.  If the
                 // rule set both rules will belong to is a fraction rule
diff --git a/icu4j/main/core/src/test/java/com/ibm/icu/dev/test/format/RBNFParseTest.java b/icu4j/main/core/src/test/java/com/ibm/icu/dev/test/format/RBNFParseTest.java
@@ -213,6 +213,17 @@ public void Test23184EmptyRuleSet() {
     public void TestNullRuleSet() {
         try {
             RuleBasedNumberFormat rbnf = new RuleBasedNumberFormat("x00:a>>>b>#>", Locale.US);
+            errln("Failed: should throw IllegalArgumentException");
+        } catch (IllegalArgumentException e) {
+            // success!
+        }
+    }
+
+    @Test
+    public void TestDividedByZero() {
+        try {
+            RuleBasedNumberFormat rbnf = new RuleBasedNumberFormat("7060920374060940374/4:[]");
+            errln("Failed: should throw IllegalArgumentException");
         } catch (IllegalArgumentException e) {
             // success!
         }
