fix(cli): prevent CPU hang and quote swallowing on @ within code (#29434) - #29557

Summary

Fixes an uninterruptible 100% CPU lockup in headless / non-interactive mode (-p with piped stdin) caused by catastrophic quote-swallowing when code contains scoped packages (@scope/pkg) followed by quoted strings. Incorporates reviewer feedback to protect against brace-expansion ReDoS in minimatch, sanitize paths against directory traversal (..), and exclude absolute paths and glob metacharacters from fallback searches.

Details

Problem

1. When input is piped to gemini -p, atCommandProcessor scans for @<path> references.
2. In AT_COMMAND_PATH_REGEX_SOURCE, the double-quoted string branch "(?:[^"]*)" was nested inside a repeated outer group (?: ... )+ and allowed arbitrary characters (including newlines and delimiters) across unescaped quotes.
3. When parsing code such as import { useThing } from "@scope/pkg"; followed by subsequent imports or quoted strings, the @ inside quotes was matched and the closing quote after pkg was parsed as the start of a "(?:[^"]*)" quoted span. This greedily swallowed entire source files (thousands of characters across tens or hundreds of lines) into a single @path token.
4. When direct resolution failed, resolveFilePaths fell back to recursive glob search (config.getEnableRecursiveFileSearch()), constructing **/*${pathName}* with the unvalidated multi-kilobyte string.
5. In npm glob / minimatch, the presence of dozens of import statements with curly braces ({ a, b, c }) triggered combinatorial explosion in brace-expansion (reaching its ceiling of 100,000 patterns) and synchronous preprocessing in minimatch on the Node main V8 thread. This starved the event loop, pegged CPU at 100%, and ignored SIGINT / SIGTERM / AbortSignal.

Solution

1. Tighten AT_COMMAND_PATH_REGEX_SOURCE (atCommandProcessor.ts):
   • Disallow newlines inside double-quoted paths ("[^"\n\r]*").
   • Separate quoted path alternatives from unquoted paths so an unquoted path cannot seamlessly chain into a quoted span across quotes.
   • Add quotes (", ', `) to delimiters for unquoted path tokens so unquoted paths stop immediately before quotes.
2. Pre-Glob Defense-in-Depth Guard (resolveFilePaths in atCommandProcessor.ts):
   • Enforce that pathName.length > 0 && pathName.length <= MAX_GLOB_SEARCH_PATH_LENGTH (255) && !path.isAbsolute(pathName) && !pathName.includes('..') && !/[\r\n\t\0{}*?\[\]]/.test(pathName) before invoking globTool.buildAndExecute.
   • Disallows newlines, null bytes, and curly braces ({, }) in recursive glob search paths, eliminating combinatorial brace expansion in minimatch (per code review feedback #5355588500).
   • Sanitizes paths against directory traversal sequences (..) to prevent path traversal during glob fallback (per code review feedback #5356587921).
   • Excludes absolute paths (!path.isAbsolute(pathName)) and glob metacharacters (*, ?, [, ], \t) to prevent invalid search patterns and runaway wildcard matching (per code review feedback #5356733854).
   • Preserves token reporting and telemetry integrity without breaking backwards compatibility.

Related Issues

Fixes #29434

How to Validate

1. Automated Vitest Tests

Run the updated regression test suite:

npm test -w @google/gemini-cli -- src/ui/hooks/atCommandProcessor.test.ts

Expected: All 72 tests pass, including:

• does not greedily consume code across quotes when @ is inside quotes (#29434)
• does not hang when input contains @scope/pkg followed by many imports (#29434)
• does not invoke recursive glob search on paths exceeding MAX_GLOB_SEARCH_PATH_LENGTH (#29434)
• does not invoke recursive glob search on paths containing newlines (#29434)
• does not invoke recursive glob search on paths containing curly braces (#29434)
• does not invoke recursive glob search on paths containing directory traversal sequences (#29434)
• does not invoke recursive glob search on absolute paths that do not exist (#29434)
• does not invoke recursive glob search on paths containing glob wildcards (#29434)

2. Manual Reproduction Verification

Create a test file with 60 TypeScript/ESM imports:

node -e '
let content = `import { useThing } from "@scope/pkg";\n`;
for (let i = 1; i <= 60; i++) {
  content += `import { alpha${i}, beta${i}, gamma${i} } from "~/modules/feature${i}/index";\n`;
}
fs.writeFileSync("/tmp/repro.txt", content);
'
cat /tmp/repro.txt | node bundle/gemini.js --skip-trust --approval-mode plan -p "Summarize"

Expected: The CLI processes the input and dispatches to the model in < 1 second instead of freezing at 100% CPU.

3. File Reference Regressions

Verify that standard @path/to/file.txt, escaped spaces (@path\ with\ spaces/file.txt), and Windows quoted paths (@"path with spaces/file.txt") continue to resolve and attach correctly.

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Validated on required platforms/methods:
  • MacOS
    • npm run
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • Linux
    • npm run
    • npx
    • Docker