fix(awk): cap multi-subscript arrays#2046
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Pull request overview
This PR hardens the AWK parser against DoS by bounding the number of comma-separated subscripts permitted in multi-subscript array indexing (a[e1,e2,...]), preventing unbounded left-deep SUBSEP_CONCAT AST construction.
Changes:
- Introduces a centralized
AWK_MAX_MULTI_SUBSCRIPTSlimit (default 100) inbuiltins/limits.rs. - Enforces the cap during AWK parsing when collecting comma-separated subscripts, emitting
awk: too many array subscriptson overflow. - Adds a regression test to ensure excessive multi-subscript lists are rejected while preserving existing behavior.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| crates/bashkit/src/builtins/limits.rs | Adds a centralized AWK multi-subscript cap constant. |
| crates/bashkit/src/builtins/awk/parser.rs | Enforces the cap while parsing multi-subscript array access to prevent left-deep AST DoS. |
| crates/bashkit/src/builtins/awk/tests.rs | Adds a regression test covering rejection of overly long multi-subscript lists. |
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| #[tokio::test] | ||
| async fn test_awk_rejects_too_many_multi_subscripts() { | ||
| // Regression: unbounded multi-subscript lists built a recursive SUBSEP_CONCAT AST. | ||
| let subscripts = std::iter::repeat_n("1", 101).collect::<Vec<_>>().join(","); |
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| Status | Name | Latest Commit | Preview URL | Updated (UTC) |
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| ✅ Deployment successful! View logs |
bashkit | 9cd76fb | Commit Preview URL | Jun 12 2026, 01:35 AM |
chaliy
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Jun 12, 2026
Closes #2046 Introduces `AWK_MAX_MULTI_SUBSCRIPTS` (100) and enforces it at **parse time** when collecting comma-separated subscripts in `arr[e1,e2,...]` expressions. The parser rejects any subscript list longer than the cap, preventing pathological left-deep `SUBSEP_CONCAT` AST construction from adversarial scripts. Adds a regression test that verifies rejection when the cap is exceeded (using `AWK_MAX_MULTI_SUBSCRIPTS + 1` so it tracks the constant).
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Superseded by #2055 — rebased cleanly on main.