Commit 510ebd7

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mruby-compiler: terminate parsing early after too many errors

When parsing malformed input with many syntax errors (e.g., via eval with a long garbage string), the parser would continue until the end of input, causing long execution times. Add an early termination check in the lexer that returns EOF once the error count exceeds 10 (same as error_buffer size). This prevents DoS from inputs like eval("garbage" * 1000). Co-authored-by: Claude <noreply@anthropic.com>

2 files changed

Lines changed: 2361 additions & 2286 deletions

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mrbgems/mruby-compiler/core

Lines changed: 5 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -6120,6 +6120,11 @@ parser_yylex(parser_state *p)`
`6120`	`6120`	`enum mrb_lex_state_enum last_state;`
`6121`	`6121`	`int token_column;`
`6122`	`6122`
	`6123`	`+/* Early termination if too many errors - prevents DoS from malformed input */`
	`6124`	`+if (p->nerr > 10) {`
	`6125`	`+return 0; /* EOF */`
	`6126`	`+ }`
	`6127`	`+`
`6123`	`6128`	`if (p->lex_strterm) {`
`6124`	`6129`	`if (is_strterm_type(p, STR_FUNC_HEREDOC)) {`
`6125`	`6130`	`if (p->parsing_heredoc != NULL)`