Defensively cap number_of_leading_zeros to prevent OOM

Author: ghaithabdulreda

cpp/src/phonenumbers/phonenumberutil.cc

@@ -2678,10 +2678,11 @@ void PhoneNumberUtil::GetNationalSignificantNumber(
     string* national_number) const {
   DCHECK(national_number);
   // If leading zero(s) have been set, we prefix this now. Note this is not a
-  // national prefix. Ensure the number of leading zeros is at least 0 so we
-  // don't crash in the case of malicious input.
+  // national prefix. Defensively cap the number of leading zeros to avoid OOM
+  // from malicious input. Ensure the number of leading zeros is at least 0 so
+  // we don't crash in the case of malicious input.
   StrAppend(national_number, number.italian_leading_zero() ?
-      string(std::max(number.number_of_leading_zeros(), 0), '0') : "");
+      string(std::min(std::max(number.number_of_leading_zeros(), 0), 3), '0') : "");
   StrAppend(national_number, number.national_number());
 }
 

java/libphonenumber/src/com/google/i18n/phonenumbers/PhoneNumberUtil.java

@@ -1928,9 +1928,11 @@ public String formatOutOfCountryKeepingAlphaChars(PhoneNumber number,
    */
   public String getNationalSignificantNumber(PhoneNumber number) {
     // If leading zero(s) have been set, we prefix this now. Note this is not a national prefix.
+    // Defensively cap the number of leading zeros to avoid OOM from malicious input.
     StringBuilder nationalNumber = new StringBuilder();
     if (number.isItalianLeadingZero() && number.getNumberOfLeadingZeros() > 0) {
-      char[] zeros = new char[number.getNumberOfLeadingZeros()];
+      int numberOfLeadingZeros = Math.min(number.getNumberOfLeadingZeros(), 3);
+      char[] zeros = new char[numberOfLeadingZeros];
       Arrays.fill(zeros, '0');
       nationalNumber.append(new String(zeros));
     }