Do not complete pause if we're not running

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 17 insertions, 43 deletions

diff --git a/wintun.c b/wintun.c
index 9ba1b1f..ffca16d 100644
--- a/wintun.c
+++ b/wintun.c
@@ -799,9 +799,6 @@ static NTSTATUS
 TunDispatchWrite(_Inout_ TUN_CTX *Ctx, _Inout_ IRP *Irp)
 {
     NTSTATUS Status;
-
-    InterlockedIncrement64(&Ctx->ActiveNBLCount);
-
     IO_STACK_LOCATION *Stack = IoGetCurrentIrpStackLocation(Irp);
     ULONG Size = Stack->Parameters.Write.Length;
     if (Status = STATUS_INVALID_USER_BUFFER, (Size < TUN_EXCH_MIN_BUFFER_SIZE_WRITE || Size > TUN_EXCH_MAX_BUFFER_SIZE))
@@ -823,11 +820,6 @@ TunDispatchWrite(_Inout_ TUN_CTX *Ctx, _Inout_ IRP *Irp)
     if (Status = STATUS_INSUFFICIENT_RESOURCES, !Mdl)
         goto cleanup_ExFreePoolWithTag;
 
-    KIRQL Irql = ExAcquireSpinLockShared(&Ctx->TransitionLock);
-    LONG Flags = InterlockedGet(&Ctx->Flags);
-    if (Status = STATUS_FILE_FORCED_CLOSED, !(Flags & TUN_FLAGS_PRESENT))
-        goto cleanup_ExReleaseSpinLockShared;
-
     const UCHAR *BufferPos = BufferStart, *BufferEnd = BufferStart + Size;
     typedef enum
     {
@@ -852,24 +844,14 @@ TunDispatchWrite(_Inout_ TUN_CTX *Ctx, _Inout_ IRP *Irp)
     LONG NblCount = 0;
     while (BufferEnd - BufferPos >= sizeof(TUN_PACKET))
     {
-        if (NblCount >= MAXLONG)
-        {
-            Status = STATUS_INVALID_USER_BUFFER;
+        if (Status = STATUS_INVALID_USER_BUFFER, NblCount >= MAXLONG)
             goto cleanup_nbl_queues;
-        }
-
         TUN_PACKET *Packet = (TUN_PACKET *)BufferPos;
-        if (Packet->Size > TUN_EXCH_MAX_IP_PACKET_SIZE)
-        {
-            Status = STATUS_INVALID_USER_BUFFER;
+        if (Status = STATUS_INVALID_USER_BUFFER, Packet->Size > TUN_EXCH_MAX_IP_PACKET_SIZE)
             goto cleanup_nbl_queues;
-        }
         ULONG AlignedPacketSize = TunPacketAlign(sizeof(TUN_PACKET) + Packet->Size);
-        if (BufferEnd - BufferPos < (ptrdiff_t)AlignedPacketSize)
-        {
-            Status = STATUS_INVALID_USER_BUFFER;
+        if (Status = STATUS_INVALID_USER_BUFFER, (BufferEnd - BufferPos < (ptrdiff_t)AlignedPacketSize))
             goto cleanup_nbl_queues;
-        }
 
         EtherTypeIndex Index;
         if (Packet->Size >= 20 && Packet->Data[0] >> 4 == 4)
@@ -884,11 +866,8 @@ TunDispatchWrite(_Inout_ TUN_CTX *Ctx, _Inout_ IRP *Irp)
 
         NET_BUFFER_LIST *Nbl = NdisAllocateNetBufferAndNetBufferList(
             Ctx->NBLPool, 0, 0, Mdl, (ULONG)(Packet->Data - BufferStart), Packet->Size);
-        if (!Nbl)
-        {
-            Status = STATUS_INSUFFICIENT_RESOURCES;
+        if (Status = STATUS_INSUFFICIENT_RESOURCES, !Nbl)
             goto cleanup_nbl_queues;
-        }
 
         Nbl->SourceHandle = Ctx->MiniportAdapterHandle;
         NdisSetNblFlag(Nbl, EtherTypeConstants[Index].NblFlags);
@@ -901,29 +880,25 @@ TunDispatchWrite(_Inout_ TUN_CTX *Ctx, _Inout_ IRP *Irp)
         BufferPos += AlignedPacketSize;
     }
 
-    if ((ULONG)(BufferPos - BufferStart) != Size)
-    {
-        Status = STATUS_INVALID_USER_BUFFER;
+    if (Status = STATUS_INVALID_USER_BUFFER, (ULONG)(BufferPos - BufferStart) != Size)
         goto cleanup_nbl_queues;
-    }
     Irp->IoStatus.Information = Size;
 
-    if (!NblCount)
-    {
-        Status = STATUS_SUCCESS;
-        goto cleanup_ExReleaseSpinLockShared;
-    }
-    if (!(Flags & TUN_FLAGS_RUNNING))
+    if (Status = STATUS_SUCCESS, !NblCount)
+        goto cleanup_nbl_queues;
+
+    KIRQL Irql = ExAcquireSpinLockShared(&Ctx->TransitionLock);
+    LONG Flags = InterlockedGet(&Ctx->Flags);
+    if ((Status = STATUS_FILE_FORCED_CLOSED, !(Flags & TUN_FLAGS_PRESENT)) ||
+        (Status = STATUS_SUCCESS, !(Flags & TUN_FLAGS_RUNNING)))
     {
         InterlockedAdd64((LONG64 *)&Ctx->Statistics.ifInDiscards, NblCount);
         InterlockedAdd64((LONG64 *)&Ctx->Statistics.ifInErrors, NblCount);
-        Status = STATUS_SUCCESS;
-        goto cleanup_nbl_queues;
+        goto cleanup_ExReleaseSpinLockShared;
     }
 
-    InterlockedAdd64(&Ctx->ActiveNBLCount, NblCount);
+    InterlockedAdd64(&Ctx->ActiveNBLCount, NblCount + 1);
     *MdlRefcount = NblCount;
-
     for (EtherTypeIndex Index = EtherTypeIndexStart; Index < EtherTypeIndexEnd; Index++)
     {
         if (!NblQueue[Index].Head)
@@ -937,10 +912,12 @@ TunDispatchWrite(_Inout_ TUN_CTX *Ctx, _Inout_ IRP *Irp)
     }
 
     ExReleaseSpinLockShared(&Ctx->TransitionLock, Irql);
-    TunCompleteRequest(Ctx, Irp, STATUS_SUCCESS, IO_NETWORK_INCREMENT);
     TunCompletePause(Ctx, TRUE);
+    TunCompleteRequest(Ctx, Irp, STATUS_SUCCESS, IO_NETWORK_INCREMENT);
     return STATUS_SUCCESS;
 
+cleanup_ExReleaseSpinLockShared:
+    ExReleaseSpinLockShared(&Ctx->TransitionLock, Irql);
 cleanup_nbl_queues:
     for (EtherTypeIndex Index = EtherTypeIndexStart; Index < EtherTypeIndexEnd; Index++)
     {
@@ -951,14 +928,11 @@ cleanup_nbl_queues:
             NdisFreeNetBufferList(Nbl);
         }
     }
-cleanup_ExReleaseSpinLockShared:
-    ExReleaseSpinLockShared(&Ctx->TransitionLock, Irql);
     NdisFreeMdl(Mdl);
 cleanup_ExFreePoolWithTag:
     ExFreePoolWithTag(BufferStart, TUN_MEMORY_TAG);
 cleanup_CompleteRequest:
     TunCompleteRequest(Ctx, Irp, Status, IO_NO_INCREMENT);
-    TunCompletePause(Ctx, TRUE);
     return Status;
 }