Fatal error: Can't take a prefix of negative length from a collection

[buhikon]

Summary

A crash occurred on STPFormTextField

Code to reproduce

1. Launch a sample called UI Examples on iPad (device or simulator)
2. Select the first cell (Card Field) from the table view on the main screen
3. (a new view controller will be displayed, and a credit card text field will be automatically focused and a keyboard will appear)
4. Tap a space bar in the keyboard
5. Tap a backspace in the keyboard
6. (crash)

iOS version

15.1

Installation method

Tested on the sample app

SDK version

21.9.0

Other information

(STPFormTextField.swift)

404        if deleting {
405            if let sanitized = unformattedString(for: textField.text) {
406                inputText = sanitized.stp_safeSubstring(to: sanitized.count - 1)
407            }
408        } else {

when the crash happens,

• the value of textField.text is " " (Line 405)
• sanitized is "" (Line 405)
• it tries to call stp_safeSubstringfunc with -1 that makes the crash (Line 406)

[ramont-stripe]

@buhikon thank you for reporting this issue! I was able to reproduce it by following the provided steps. We are working on a fix for this.

[ramont-stripe]

Hi @buhikon,

We just released a fix for this in v21.10.0. I'm closing this issue for now; feel free to re-open it if you are still experiencing this issue after upgrading.

Thank you again for reporting this and providing very detailed steps on how to reproduce it!