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fix(runner): reject NUL bytes in file paths #46

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fix(runner): reject NUL bytes in file paths #46

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8 changes: 8 additions & 0 deletions api/src/validation.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -126,6 +126,10 @@ describe('validateFilePath', () => {
expect(() => validateFilePath('.', submissionDir)).toThrow(ValidationError);
});

it('rejects NUL bytes in file names', () => {
expect(() => validateFilePath('file\0.txt', submissionDir)).toThrow(/NUL/);
});

it('rejects path traversal with .. segments', () => {
expect(() => validateFilePath('../etc/passwd', submissionDir)).toThrow(ValidationError);
expect(() => validateFilePath('a/../../escape', submissionDir)).toThrow(ValidationError);
Expand Down Expand Up @@ -188,4 +192,8 @@ describe('isValidFilePath', () => {
expect(isValidFilePath('', submissionDir)).toBe(false);
expect(isValidFilePath('a'.repeat(MAX_LEN + 10), submissionDir)).toBe(false);
});

it('returns false for paths containing NUL bytes', () => {
expect(isValidFilePath('file\0.txt', submissionDir)).toBe(false);
});
});
3 changes: 3 additions & 0 deletions api/src/validation.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,9 @@ export function validateFilePath(name: string, submissionDir: string): void {
if (!name || name === '.') {
throw new ValidationError('File path must not be empty');
}
if (name.includes('\0')) {
throw new ValidationError('File path must not contain NUL bytes');
}
/* Reject absolute paths up front. `path.resolve(submissionDir, name)`
* ignores `submissionDir` when `name` is absolute, so an absolute path
* that happens to point inside `submissionDir` (e.g. the exact on-disk
Expand Down