typedef struct _REPROTECT_CONTEXT
{
PMDL Mdl;
PUCHAR LockedVa;
} REPROTECT_CONTEXT, * PREPROTECT_CONTEXT;
NTSTATUS
MmLockVaForWrite(
__in PVOID Va,
__in ULONG Length,
__out PREPROTECT_CONTEXT ReprotectContext
)
{
NTSTATUS Status;
Status = STATUS_SUCCESS;
ReprotectContext->Mdl = 0;
ReprotectContext->LockedVa = 0;
ReprotectContext->Mdl = IoAllocateMdl(
Va,
Length,
FALSE,
FALSE,
0
);
if (!ReprotectContext->Mdl)
{
return STATUS_INSUFFICIENT_RESOURCES;
}
__try
{
MmProbeAndLockPages(
ReprotectContext->Mdl,
KernelMode,
IoModifyAccess
);
}
__except (EXCEPTION_EXECUTE_HANDLER)
{
return GetExceptionCode();
}
ReprotectContext->LockedVa = (PUCHAR)MmMapLockedPagesSpecifyCache(
ReprotectContext->Mdl,
KernelMode,
MmCached,
0,
FALSE,
NormalPagePriority
);
if (!ReprotectContext->LockedVa)
{
IoFreeMdl(
ReprotectContext->Mdl
);
ReprotectContext->Mdl = 0;
return STATUS_ACCESS_VIOLATION;
}
Status = MmProtectMdlSystemAddress(
ReprotectContext->Mdl,
PAGE_EXECUTE_READWRITE
);
if (!NT_SUCCESS(Status))
{
MmUnmapLockedPages(
ReprotectContext->LockedVa,
ReprotectContext->Mdl
);
MmUnlockPages(
ReprotectContext->Mdl
);
IoFreeMdl(
ReprotectContext->Mdl
);
ReprotectContext->LockedVa = 0;
ReprotectContext->Mdl = 0;
}
return Status;
}
NTSTATUS
MmUnlockVaForWrite(
__in PREPROTECT_CONTEXT ReprotectContext
)
{
if (ReprotectContext->LockedVa)
{
MmUnmapLockedPages(
ReprotectContext->LockedVa,
ReprotectContext->Mdl
);
MmUnlockPages(
ReprotectContext->Mdl
);
IoFreeMdl(
ReprotectContext->Mdl
);
ReprotectContext->LockedVa = 0;
ReprotectContext->Mdl = 0;
}
return STATUS_SUCCESS;
}