Skip to content

Replace recursive regex with linear scan in isAlphaNumber() to fix StackOverflowError #4017

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
bann6578-boop wants to merge 2 commits into
base: master
Choose a base branch
from
+17 −1
Open

Replace recursive regex with linear scan in isAlphaNumber() to fix StackOverflowError #4017

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
ad29f17
Add input length bound to isAlphaNumber() to prevent StackOverflowError
bann6578-boop Jun 20, 2026
b4b7247
Add input length bound and replace regex in isAlphaNumber() to preven…
bann6578-boop Jun 20, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
18 changes: 17 additions & 1 deletion java/libphonenumber/src/com/google/i18n/phonenumbers/PhoneNumberUtil.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2563,14 +2563,30 @@ public boolean isNANPACountry(String regionCode) {
* @param number the number that needs to be checked
* @return true if the number is a valid vanity number
*/
private static boolean hasAtLeastThreeAlphaChars(CharSequence number) {
int alphaCount = 0;
for (int i = 0; i < number.length(); i++) {
char c = number.charAt(i);
if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) {
if (++alphaCount >= 3) {
return true;
}
}
}
return false;
}

public boolean isAlphaNumber(CharSequence number) {
if (number.length() > MAX_INPUT_STRING_LENGTH) {
return false;
}
if (!isViablePhoneNumber(number)) {
// Number is too short, or doesn't match the basic phone number pattern.
return false;
}
StringBuilder strippedNumber = new StringBuilder(number);
maybeStripExtension(strippedNumber);
return VALID_ALPHA_PHONE_PATTERN.matcher(strippedNumber).matches();
return hasAtLeastThreeAlphaChars(strippedNumber);
}

/**
Expand Down
Loading