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fix(heap): eliminate TOCTOU gap in _ExFreePoolWithTracking #9

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Merged
TorinKS merged 1 commit into from
Mar 22, 2026
Merged

fix(heap): eliminate TOCTOU gap in _ExFreePoolWithTracking #9

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10 changes: 6 additions & 4 deletions src/KernelHeap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -352,9 +352,11 @@ void _ExFreePoolWithTracking(PVOID pointer, const char* FileName, int LineNumber
HEAP_VERBOSE("_ExFreePoolWithTracking: State info - heap handle: %p, TrackFreedMemory: %d",
state->HeapHandle, state->TrackFreedMemory);

if (state->TrackFreedMemory) {
EnterCriticalSection(&state->TrackingLock);
/* Hold TrackingLock across double-free check AND untrack to prevent TOCTOU.
* CRITICAL_SECTION is recursive, so UntrackAllocation can re-enter safely. */
EnterCriticalSection(&state->TrackingLock);

if (state->TrackFreedMemory) {
PLIST_ENTRY current = state->MemoryAllocations.Flink;
while (current != &state->MemoryAllocations) {
PMEMORY_TRACKING_ENTRY entry = CONTAINING_RECORD(current, MEMORY_TRACKING_ENTRY, ListEntry);
Expand All @@ -375,13 +377,13 @@ void _ExFreePoolWithTracking(PVOID pointer, const char* FileName, int LineNumber
}
HEAP_TRACE("_ExFreePoolWithTracking: No double-free detected for %p", pointer);
}

LeaveCriticalSection(&state->TrackingLock);
}

HEAP_TRACE("_ExFreePoolWithTracking: Calling UntrackAllocation for %p", pointer);
found = UntrackAllocation(pointer, FileName, LineNumber);

LeaveCriticalSection(&state->TrackingLock);

HEAP_VERBOSE("_ExFreePoolWithTracking: UntrackAllocation returned %d for %p", found, pointer);

if (!found && !state->SuppressErrors) {
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