fix: prevent StackOverflowError converting large mSync values#2269
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MSYNC_INPUT_VALUE_PATTERN matched the JSON value with the group ((?:[^"\]|\.)*). On OpenJDK this quantified alternation recurses once per repetition, so a large mSync value (e.g. a big text-area payload in a recorded UIDL POST) exhausts the call stack and the HAR-to-k6 conversion dies with a StackOverflowError. Replace the group with ((?:[^"\]++|\.)*+), using a possessive quantifier on the character class and a possessive outer star. The non-quote/ non-backslash runs are now consumed in a single pass with no backtracking, eliminating the per-character recursion. The match and capture semantics are unchanged: it still captures any run of non-"/non-\ characters and \-escapes up to the closing quote. Add HarToK6ConverterTest#largeMsyncValueDoesNotOverflowStack. Fixes: #2266
caalador
approved these changes
Jun 23, 2026
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MSYNC_INPUT_VALUE_PATTERN matched the JSON value with the group
((?:[^"\]|\.)*).On OpenJDK this quantified alternation recurses once per repetition, so a large mSync value (e.g. a big text-area payload in a recorded UIDL POST) exhausts the call stack and the HAR-to-k6 conversion dies with a StackOverflowError.Replace the group with
((?:[^"\]++|\.)*+), using a possessive quantifier on the character class and a possessive outer star. The non-quote/ non-backslash runs are now consumed in a single pass with no backtracking, eliminating the per-character recursion. The match and capture semantics are unchanged: it still captures any run of non-"/non-\ characters and\-escapes up to the closing quote.Add HarToK6ConverterTest#largeMsyncValueDoesNotOverflowStack.
Fixes: #2266