fix(OSQUERY-003): CU-86akhf8u2 genSudoersFile ignores unchecked substr/at() calls on possibly malformed sudoers lines

[flamingo]

Closes findings from rule OSQUERY-003 — genSudoersFile ignores unchecked substr/at() calls on possibly malformed sudoers lines.

Draft — this is a starting point, not a finished change. The fix required judgment, so read it before trusting it.

#	Fix confidence	Finding	Location
1	🟡 85 medium	genSudoersFile ignores unchecked substr/at() calls on possibly malformed sudoers lines	osquery/tables/system/posix/sudoers.cpp:118

What changed — and what was deliberately left — is explained per finding as inline review comments on the lines each finding touched.

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Run: https://product-hub.flamingo.so/admin/code-review
Run id: 39233833-f1d6-416e-93a7-71af15e3e968

Merging this PR is recorded as acceptance of the rule that produced it;
closing it unmerged is recorded as rejection. Both feed rule health, so
closing a wrong suggestion is useful rather than merely tidy.

ClickUp task: CU-86akhf8u2 Osquery review findings sweep (15 PRs)

[flamingo]

🦩 What this fix changed, finding by finding

1 finding(s) fixed in this draft — 1 explained inline on the diff.

[flamingo]

🦩 🔴 genSudoersFile ignores unchecked substr/at() calls on possibly malformed sudoers lines

In genSudoersFile (osquery/tables/system/posix/sudoers.cpp), the two rule_details.at(0) calls under the is_includedir and is_include branches are now guarded with !rule_details.empty() before indexing, and an explicit empty-string check (with a TLOG message and continue) was added right after each path-normalization block to avoid passing an empty string into listFilesInDirectory/recursive genSudoersFile calls. This removes the possibility of an uncaught std::out_of_range from .at(0) on a malformed/empty rule_details value while preserving existing control flow and style.

🤖 Prompt for AI agents

In osquery/tables/system/posix/sudoers.cpp around line 118, review and complete this code-review fix: genSudoersFile ignores unchecked substr/at() calls on possibly malformed sudoers lines.
What the draft fix changed: In genSudoersFile (osquery/tables/system/posix/sudoers.cpp), the two `rule_details.at(0)` calls under the `is_includedir` and `is_include` branches are now guarded with `!rule_details.empty()` before indexing, and an explicit empty-string check (with a TLOG message and `continue`) was added right after each path-normalization block to avoid passing an empty string into `listFilesInDirectory`/recursive `genSudoersFile` calls. This removes the possibility of an uncaught `std::out_of_range` from `.at(0)` on a malformed/empty rule_details value while preserving existing control flow and style.
Verify the change is correct and complete; do not refactor unrelated code.

fix confidence: 🟡 85 medium — react 👍/👎 to teach the reviewer