From 912703cd7769fd447028842d7fecf09d25a4dfe6 Mon Sep 17 00:00:00 2001
From: Bill Zissimopoulos <billziss@navimatics.com>
Date: Fri, 30 Oct 2020 15:39:56 -0700
Subject: [PATCH] sys: FspBufferUserBuffer: special case Irp->UserBuffer kernel
 address

---
 src/sys/util.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/sys/util.c b/src/sys/util.c
index 58d26a81..da27bc62 100644
--- a/src/sys/util.c
+++ b/src/sys/util.c
@@ -608,6 +608,13 @@ NTSTATUS FspBufferUserBuffer(PIRP Irp, ULONG Length, LOCK_OPERATION Operation)
     if (0 == Length || 0 != Irp->AssociatedIrp.SystemBuffer)
         return STATUS_SUCCESS;
 
+    if (KernelMode == Irp->RequestorMode &&
+        (PUINT8)MM_SYSTEM_RANGE_START <= (PUINT8)Irp->UserBuffer)
+    {
+        Irp->AssociatedIrp.SystemBuffer = Irp->UserBuffer;
+        return STATUS_SUCCESS;
+    }
+
     PVOID SystemBuffer = FspAllocNonPagedExternal(Length);
     if (0 == SystemBuffer)
         return STATUS_INSUFFICIENT_RESOURCES;