[PATCH 1/3] fix possible TunDispatchSecurityDescriptor leak.

[godisgovernment at gmail.com (Shawn Hoffman)]

TunDispatchSecurityDescriptor will leak if second
RtlAbsoluteToSelfRelativeSD fails. Practically this can't happen, but
from wintun code it's unclear.

Signed-off-by: Shawn Hoffman <godisgovernment at gmail.com>
---
 wintun.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/wintun.c b/wintun.c
index 624de2f..90e7930 100644
--- a/wintun.c
+++ b/wintun.c
@@ -820,6 +820,14 @@ static NTSTATUS TunInitializeDispatchSecurityDescriptor(VOID)
     return STATUS_SUCCESS;
 }
 
+static VOID TunFreeDispatchSecurityDescriptor(VOID)
+{
+    if (!TunDispatchSecurityDescriptor)
+        return;
+    ExFreePoolWithTag(TunDispatchSecurityDescriptor, TUN_MEMORY_TAG);
+    TunDispatchSecurityDescriptor = NULL;
+}
+
 _IRQL_requires_max_(PASSIVE_LEVEL)
 static VOID
 TunProcessNotification(HANDLE ParentId, HANDLE ProcessId, BOOLEAN Create)
@@ -1387,7 +1395,7 @@ TunUnload(PDRIVER_OBJECT DriverObject)
     NdisMDeregisterMiniportDriver(NdisMiniportDriverHandle);
     ExDeleteResourceLite(&TunDispatchCtxGuard);
     ExDeleteResourceLite(&TunDispatchDeviceListLock);
-    ExFreePoolWithTag(TunDispatchSecurityDescriptor, TUN_MEMORY_TAG);
+    TunFreeDispatchSecurityDescriptor();
 }
 
 DRIVER_INITIALIZE DriverEntry;
@@ -1398,7 +1406,7 @@ DriverEntry(DRIVER_OBJECT *DriverObject, UNICODE_STRING *RegistryPath)
     NTSTATUS Status;
 
     if (!NT_SUCCESS(Status = TunInitializeDispatchSecurityDescriptor()))
-        return Status;
+        goto cleanupSD;
 
     NdisVersion = NdisGetVersion();
     if (NdisVersion < NDIS_MINIPORT_VERSION_MIN)
@@ -1461,6 +1469,7 @@ cleanupNotifier:
 cleanupResources:
     ExDeleteResourceLite(&TunDispatchCtxGuard);
     ExDeleteResourceLite(&TunDispatchDeviceListLock);
-    ExFreePoolWithTag(TunDispatchSecurityDescriptor, TUN_MEMORY_TAG);
+cleanupSD:
+    TunFreeDispatchSecurityDescriptor();
     return Status;
 }
-- 
2.26.2.windows.1