ExFreePool2 - NtDoc
Native API online documentation, based on the System Informer
(formerly Process Hacker) phnt
headers
// wdm.h
VOID ExFreePool2(
[in] PVOID P,
[in] ULONG Tag,
[in, optional] PCPOOL_EXTENDED_PARAMETER ExtendedParameters,
[in] ULONG ExtendedParametersCount
);
View the official Windows Driver Kit DDI referenceNo description available.
The ExFreePool2 routine deallocates a previously allocated block of pool memory. It extends ExFreePool by accepting optional extended parameters to free allocations associated with a secure pool created via ExCreatePool.
P [in]Pointer to the start of the allocation to free. Must be the exact address returned by the pool allocation routine such as ExAllocatePool2 or ExAllocatePool3. This parameter must not be NULL.
Tag [in]Pool tag originally supplied when the allocation was made.
ExtendedParameters [in, optional]Pointer to an array of extended parameter descriptors (type POOL_EXTENDED_PARAMETER). See Remarks.
ExtendedParametersCount [in]Number of entries in the ExtendedParameters array. See Remarks.
The following table shows the requirements for using ExFreePool2 with different types of allocations:
| Allocation Type | ExtendedParametersCount | ExtendedParameters |
|---|---|---|
| Ordinary (non-secure) | 0 | NULL |
| Secure | 1 | Pointer to POOL_EXTENDED_PARAMS_SECURE_POOL structure |
For secure pool frees, the associated POOL_EXTENDED_PARAMS_SECURE_POOL structure must:
Validation failures (wrong count, unsupported parameter type, non-zero reserved fields, invalid handle, or secure kernel communication failure) cause a bug check (BAD_POOL_CALLER) rather than returning an error status.
This routine doesn't return an NTSTATUS value; it always completes the free or bug checks. A double free, corrupted header, tag mismatch, or freeing with incorrect secure pool metadata can also trigger pool integrity bug checks depending on system diagnostics.
ExFreePool2 must be called at IRQL <= DISPATCH_LEVEL. If the allocation originated from paged pool the caller must be at IRQL <= APC_LEVEL. Secure pool allocations reside in nonpaged memory and can be freed at DISPATCH_LEVEL.
Use ExFreePool2 for code that may free either standard or secure pool allocations to avoid branching on allocation origin.