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fix(detector): GLOBAL_SENTINEL_REUSE — catch module-level None sentinel replay #103

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fix(detector): GLOBAL_SENTINEL_REUSE — catch module-level None sentinel replay #103

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4989034
feat(detector): GLOBAL_SENTINEL_REUSE catching null-sentinel replay
SarahLacard May 1, 2026
cbb131a
fix: catch both is None and is not None+data_ptr sentinel patterns
SarahLacard May 1, 2026
682ce9b
trigger: eval
SarahLacard May 1, 2026
52c9398
trigger: eval
SarahLacard May 1, 2026
f3b09e5
trigger: re-eval after fix
SarahLacard May 2, 2026
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17 changes: 15 additions & 2 deletions kernelguard.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3023,10 +3023,20 @@ def detect_precision_downgrade(code: str | SubmissionFacts) -> list[dict]:
})

return matches
def detect_global_sentinel_reuse(code_or_facts):
facts = ensure_submission_facts(code_or_facts)
if not facts.custom_kernel_active or not facts.ast_tree: return []
for var in facts._none_inited:
if not re.search(r'\bglobal\s+\b' + re.escape(var) + r'\b', facts.custom_kernel_active): continue
# Pattern 1: if X is None: X = ... / return X
if re.search(r'\bif\s+\b' + re.escape(var) + r'\b\s+is\s+None\b', facts.custom_kernel_active):
return [{"pattern": "GLOBAL_SENTINEL_REUSE", "severity": "high", "evidence": f"Module-level {var}=None sentinel cache (is None guard)"}]
# Pattern 2: if X is not None and X.data_ptr() == ... : return ...
if re.search(r'\bif\s+\b' + re.escape(var) + r'\b\s+is\s+not\s+None\b', facts.custom_kernel_active):
return [{"pattern": "GLOBAL_SENTINEL_REUSE", "severity": "high", "evidence": f"Module-level {var}=None sentinel cache (is not None + data_ptr guard)"}]
return []


# ---------------------------------------------------------------------------
# Score anomaly detection
# ---------------------------------------------------------------------------

def _collect_scores(metadata: Optional[dict]) -> tuple[list[float], Optional[float], Optional[float]]:
Expand Down Expand Up @@ -3653,6 +3663,7 @@ class RulePolicy:
"NEAR_CLONE_SPAM", "administrative", "support", SUSPICIOUS_ONLY, (),
(), "downgrade",
),
"GLOBAL_SENTINEL_REUSE": RulePolicy("GLOBAL_SENTINEL_REUSE", "result_reuse", "hard", AUTO_FILTER, (), (), "rewrite"),
}

BASE_SCORE_CONFIG = {
Expand Down Expand Up @@ -3790,6 +3801,7 @@ def support_only_patterns(matched_patterns: list[dict]) -> bool:
detect_thread_injection,
detect_lazy_tensor,
detect_precision_downgrade,
detect_global_sentinel_reuse,
]

BASE_DETECTOR_SPECS = [
Expand Down Expand Up @@ -3827,6 +3839,7 @@ def support_only_patterns(matched_patterns: list[dict]) -> bool:
("thread_injection", detect_thread_injection),
("lazy_tensor", detect_lazy_tensor),
("precision_downgrade", detect_precision_downgrade),
("global_sentinel_reuse", detect_global_sentinel_reuse),
]

VALID_RULE_OUTCOMES = {AUTO_FILTER, SUSPICIOUS_ONLY, TELEMETRY_ONLY}
Expand Down
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