fix(web): cap terminal hyperlink hover range scan - #7901
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Hovering an explicit OSC 8 hyperlink walked every adjacent linked cell and decoded the full attacker-controlled URI once per cell. A crafted hyperlink with a large URI spanning wrapped rows decoded viewport x URI-length bytes per hover refresh, and render frames repeat that refresh while the pointer rests on the link: a 256 KiB URI on a 200x50 grid reaches ~2.5 GB of decodes and freezes or crashes the renderer. The range walk now lives in a pure helper capped at 4096 probed cells, and URIs above 4096 chars keep the single-cell hover behavior instead of expanding across the viewport. ox-alpha via opencode
📝 WalkthroughWalkthroughThe terminal surface now resolves explicit hyperlink ranges with bounded URI length and cell scanning. ChangesHyperlink range resolution
Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: 🔵 Low · up to The change substantially bounds terminal hyperlink hover work, but one edge case can perform one more neighbor check than the stated 4096-cell limit when the first adjacent cell does not match. The PR remains mergeable with explicit owner awareness or a follow-up correction. Suggested reviewers: 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
✨ Finishing Touches 💡 1🛠️ Fix failing CI checks 💡
🧪 Generate unit tests (beta)
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Inline comments:
In `@apps/web/src/terminal/ghostty/surface.ts`:
- Around line 256-276: Update the hyperlink range scan around the backward and
forward walks so scanned increments before each hasSameHyperlink probe, counting
both matching and nonmatching attempts toward MAX_HYPERLINK_RANGE_CELLS. Add a
regression test covering a nonmatching predecessor followed by 4096 matching
successors, and verify the helper does not exceed the scan cap.
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apps/web/src/terminal/ghostty/surface.test.tsapps/web/src/terminal/ghostty/surface.ts
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The range walk incremented its budget only on matching probes, so each walk could make one probe past MAX_HYPERLINK_RANGE_CELLS. Failed probes now consume budget before their result is evaluated, making the cap an exact bound on WASM hyperlink decodes per hover refresh. ox-alpha via opencode
Problem
Hovering an explicit OSC 8 hyperlink expands the hover range by walking every adjacent linked cell (across wrapped rows) and calls
core.hyperlinkAtonce per cell. Each call allocates and decodes the full attacker-controlled URI from WASM memory, andrenderFramerepeats the walk every frame while the pointer rests on the link. A crafted terminal can emit a hyperlink with a huge URI spanning the viewport: a 256 KiB URI on a 200×50 grid reaches ~10k probes and ~2.5 GB of decoded bytes per refresh — the renderer hangs or crashes on plain terminal output.Fix
The range walk moves into an exported pure helper,
terminalExplicitHyperlinkRange, with two explicit bounds:MAX_HYPERLINK_RANGE_CELLS(4096) probed cells per walk;MAX_HYPERLINK_RANGE_URI_LENGTH(4096 chars) skip expansion entirely and keep the single-cell hover of the pre-expansion behavior.Loop semantics are unchanged otherwise (same adjacency, wrap-continuation checks, and string comparison). Worst-case work per refresh drops from unbounded to ~16 MiB of decodes.
Verification
surface.test.ts: same-row/wrapped-range expansion, stop conditions, probe-count hard cap on a fully-linked 8×600 grid, oversized URI returning a single-cell range with zero probes.runtimeAbi.test.tsfails to load in this worktree for its pre-existing.wasm?inlineimport issue, unrelated).tsgo --noEmitclean for apps/web.ox-alpha via opencode
Note
Medium Risk
Security-adjacent DoS fix on hover-path WASM URI decoding. Caps change hover highlight size for huge/spanning OSC 8 links, but the walk is otherwise the same and covered by tests.
Overview
Caps explicit OSC 8 hyperlink hover expansion so a crafted unbounded URI cannot freeze the Ghostty renderer.
The old
linkAtwalk probed every adjacent same-URI cell (including wraps) and decoded the full attacker-controlled URI on each probe, every hover frame. That walk is nowterminalExplicitHyperlinkRange: at most 4096 neighbor probes, and URIs longer than 4096 chars stay a single-cell range with no neighbor probes.Hover/activation still uses the same adjacency and wrap rules for normal links; only oversized or viewport-spanning hyperlinks get a truncated highlight. Tests cover expansion, wrap, the scan cap, and the oversized-URI short-circuit.
Reviewed by Cursor Bugbot for commit fbb94ab. Bugbot is set up for automated code reviews on this repo. Configure here.
Note
Cap terminal hyperlink hover range scan in
GhosttyTerminalSurface.linkAtGhosttyTerminalSurface.linkAtwith the newterminalExplicitHyperlinkRangehelper, which bounds scans toMAX_HYPERLINK_RANGE_CELLS(4096) and skips expansion when the URI exceedsMAX_HYPERLINK_RANGE_URI_LENGTH(4096)terminalExplicitHyperlinkRangein surface.tsMacroscope summarized fbb94ab.
Summary by CodeRabbit