datapath-windows: Use only non executable memory

Use only non-executable memory when using MmGetSystemAddressForMdlSafe.

Introduce a new function called OvsGetMdlWithLowPriority for readability.

Found using WDK 10 static code analysis.

Signed-off-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Acked-by: Shashank Ram <shashank08@gmail.com>

10 files changed, 35 insertions, 28 deletions

diff --git a/datapath-windows/ovsext/BufferMgmt.c b/datapath-windows/ovsext/BufferMgmt.c
index ff4f9bbb5..03470d787 100644
--- a/datapath-windows/ovsext/BufferMgmt.c
+++ b/datapath-windows/ovsext/BufferMgmt.c
@@ -1157,7 +1157,7 @@ FixFragmentHeader(PNET_BUFFER nb, UINT16 fragmentSize,
 
     mdl = NET_BUFFER_FIRST_MDL(nb);
 
-    bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(mdl, LowPagePriority);
+    bufferStart = (PUINT8)OvsGetMdlWithLowPriority(mdl);
     if (!bufferStart) {
         return NDIS_STATUS_RESOURCES;
     }
@@ -1215,7 +1215,7 @@ FixSegmentHeader(PNET_BUFFER nb, UINT16 segmentSize, UINT32 seqNumber,
 
     mdl = NET_BUFFER_FIRST_MDL(nb);
 
-    bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(mdl, LowPagePriority);
+    bufferStart = (PUINT8)OvsGetMdlWithLowPriority(mdl);
     if (!bufferStart) {
         return NDIS_STATUS_RESOURCES;
     }
@@ -1521,8 +1521,8 @@ OvsAllocateNBLFromBuffer(PVOID context,
 
     nb = NET_BUFFER_LIST_FIRST_NB(nbl);
     mdl = NET_BUFFER_CURRENT_MDL(nb);
-    data = (PUINT8)MmGetSystemAddressForMdlSafe(mdl, LowPagePriority) +
-                    NET_BUFFER_CURRENT_MDL_OFFSET(nb);
+    data = (PUINT8)OvsGetMdlWithLowPriority(mdl)
+        + NET_BUFFER_CURRENT_MDL_OFFSET(nb);
     if (!data) {
         OvsCompleteNBL(switchContext, nbl, TRUE);
         return NULL;
diff --git a/datapath-windows/ovsext/Datapath.c b/datapath-windows/ovsext/Datapath.c
index c68da5155..34ef2b40a 100644
--- a/datapath-windows/ovsext/Datapath.c
+++ b/datapath-windows/ovsext/Datapath.c
@@ -1593,8 +1593,7 @@ MapIrpOutputBuffer(PIRP irp,
     if (irp->MdlAddress == NULL) {
         return STATUS_INVALID_PARAMETER;
     }
-    *buffer = MmGetSystemAddressForMdlSafe(irp->MdlAddress,
-                                           NormalPagePriority);
+    *buffer = OvsGetMdlWithLowPriority(irp->MdlAddress);
     if (*buffer == NULL) {
         return STATUS_INSUFFICIENT_RESOURCES;
     }
diff --git a/datapath-windows/ovsext/Flow.c b/datapath-windows/ovsext/Flow.c
index 852a22fe6..576fe4bc5 100644
--- a/datapath-windows/ovsext/Flow.c
+++ b/datapath-windows/ovsext/Flow.c
@@ -1933,7 +1933,7 @@ GetStartAddrNBL(const NET_BUFFER_LIST *_pNB)
 
     // Ethernet Header is a guaranteed safe access.
     curMdl = (NET_BUFFER_LIST_FIRST_NB(_pNB))->CurrentMdl;
-    curBuffer =  MmGetSystemAddressForMdlSafe(curMdl, LowPagePriority);
+    curBuffer = OvsGetMdlWithLowPriority(curMdl);
     if (!curBuffer) {
         return NULL;
     }
diff --git a/datapath-windows/ovsext/Geneve.c b/datapath-windows/ovsext/Geneve.c
index 210716d5a..5692b98fb 100644
--- a/datapath-windows/ovsext/Geneve.c
+++ b/datapath-windows/ovsext/Geneve.c
@@ -157,8 +157,7 @@ NDIS_STATUS OvsEncapGeneve(POVS_VPORT_ENTRY vport,
         }
 
         curMdl = NET_BUFFER_CURRENT_MDL(curNb);
-        bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl,
-                                                           LowPagePriority);
+        bufferStart = (PUINT8)OvsGetMdlWithLowPriority(curMdl);
         if (!bufferStart) {
             status = NDIS_STATUS_RESOURCES;
             goto ret_error;
@@ -292,7 +291,7 @@ NDIS_STATUS OvsDecapGeneve(POVS_SWITCH_CONTEXT switchContext,
     curNbl = *newNbl;
     curNb = NET_BUFFER_LIST_FIRST_NB(curNbl);
     curMdl = NET_BUFFER_CURRENT_MDL(curNb);
-    bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl, LowPagePriority)
+    bufferStart = (PUINT8)OvsGetMdlWithLowPriority(curMdl)
                   + NET_BUFFER_CURRENT_MDL_OFFSET(curNb);
     if (!bufferStart) {
         status = NDIS_STATUS_RESOURCES;
diff --git a/datapath-windows/ovsext/Gre.c b/datapath-windows/ovsext/Gre.c
index 1f38ee794..afdd5abe3 100644
--- a/datapath-windows/ovsext/Gre.c
+++ b/datapath-windows/ovsext/Gre.c
@@ -202,8 +202,7 @@ OvsDoEncapGre(POVS_VPORT_ENTRY vport,
         }
 
         curMdl = NET_BUFFER_CURRENT_MDL(curNb);
-        bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl,
-                                                           LowPagePriority);
+        bufferStart = (PUINT8)OvsGetMdlWithLowPriority(curMdl);
         if (!bufferStart) {
             status = NDIS_STATUS_RESOURCES;
             goto ret_error;
diff --git a/datapath-windows/ovsext/Offload.c b/datapath-windows/ovsext/Offload.c
index 7b75e0afc..bdd9a180e 100644
--- a/datapath-windows/ovsext/Offload.c
+++ b/datapath-windows/ovsext/Offload.c
@@ -460,7 +460,7 @@ CalculateChecksumNB(const PNET_BUFFER nb,
 
     firstMdlLen = MIN(firstMdlLen, packetLen);
     if (offset < firstMdlLen) {
-        src = (PUCHAR) MmGetSystemAddressForMdlSafe(currentMdl, LowPagePriority);
+        src = (PUCHAR)OvsGetMdlWithLowPriority(currentMdl);
         if (!src) {
             return 0;
         }
@@ -485,7 +485,7 @@ CalculateChecksumNB(const PNET_BUFFER nb,
             mdlLen = MIN(mdlLen, packetLen);
         }
 
-        src = (PUCHAR)MmGetSystemAddressForMdlSafe(currentMdl, LowPagePriority);
+        src = (PUCHAR)OvsGetMdlWithLowPriority(currentMdl);
         if (!src) {
             return 0;
         }
@@ -504,7 +504,7 @@ CalculateChecksumNB(const PNET_BUFFER nb,
         csumDataLen -= csLen;
         currentMdl = NDIS_MDL_LINKAGE(currentMdl);
         if (csumDataLen && currentMdl) {
-            src = MmGetSystemAddressForMdlSafe(currentMdl, LowPagePriority);
+            src = OvsGetMdlWithLowPriority(currentMdl);
             if (!src) {
                 return 0;
             }
@@ -672,8 +672,7 @@ OvsApplySWChecksumOnNB(POVS_PACKET_HDR_INFO layers,
          curNb = curNb->Next) {
         packetLength = NET_BUFFER_DATA_LENGTH(curNb);
         curMdl = NET_BUFFER_CURRENT_MDL(curNb);
-        bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl,
-                                                           LowPagePriority);
+        bufferStart = (PUINT8)OvsGetMdlWithLowPriority(curMdl);
         if (!bufferStart) {
             return NDIS_STATUS_RESOURCES;
         }
diff --git a/datapath-windows/ovsext/PacketParser.c b/datapath-windows/ovsext/PacketParser.c
index c4a04d072..f8adcc3c9 100644
--- a/datapath-windows/ovsext/PacketParser.c
+++ b/datapath-windows/ovsext/PacketParser.c
@@ -38,8 +38,7 @@ OvsGetPacketBytes(const NET_BUFFER_LIST *nbl,
 
     // Data on current MDL may be offset from start of MDL
     while (destOffset < copyLen && currentMdl) {
-        PUCHAR srcMemory = MmGetSystemAddressForMdlSafe(currentMdl,
-                                                        LowPagePriority);
+        PUCHAR srcMemory = OvsGetMdlWithLowPriority(currentMdl);
         ULONG length = MmGetMdlByteCount(currentMdl);
         if (!srcMemory) {
             status = NDIS_STATUS_RESOURCES;
diff --git a/datapath-windows/ovsext/Stt.c b/datapath-windows/ovsext/Stt.c
index 8eb71676a..e3c4b4686 100644
--- a/datapath-windows/ovsext/Stt.c
+++ b/datapath-windows/ovsext/Stt.c
@@ -215,8 +215,7 @@ OvsDoEncapStt(POVS_VPORT_ENTRY vport,
             curNb = curNb->Next) {
         curMdl = NET_BUFFER_CURRENT_MDL(curNb);
         innerFrameLen = NET_BUFFER_DATA_LENGTH(curNb);
-        bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl,
-                                                           LowPagePriority);
+        bufferStart = (PUINT8)OvsGetMdlWithLowPriority(curMdl);
         if (bufferStart == NULL) {
             status = NDIS_STATUS_RESOURCES;
             goto ret_error;
@@ -266,7 +265,7 @@ OvsDoEncapStt(POVS_VPORT_ENTRY vport,
         ASSERT((int) (MmGetMdlByteCount(curMdl) -
                     NET_BUFFER_CURRENT_MDL_OFFSET(curNb)) >= (int) headRoom);
 
-        buf = (PUINT8) MmGetSystemAddressForMdlSafe(curMdl, LowPagePriority);
+        buf = (PUINT8)OvsGetMdlWithLowPriority(curMdl);
         if (!buf) {
             ASSERT(!"MmGetSystemAddressForMdlSafe failed");
             OVS_LOG_ERROR("MmGetSystemAddressForMdlSafe failed");
@@ -858,8 +857,7 @@ OvsDecapSetOffloads(PNET_BUFFER_LIST *curNbl,
         curNb = NET_BUFFER_LIST_FIRST_NB(*curNbl);
         curMdl = NET_BUFFER_CURRENT_MDL(curNb);
 
-        buf = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl,
-            LowPagePriority);
+        buf = (PUINT8)OvsGetMdlWithLowPriority(curMdl);
         if (buf == NULL) {
             return NDIS_STATUS_RESOURCES;
         }
diff --git a/datapath-windows/ovsext/Util.h b/datapath-windows/ovsext/Util.h
index f73c71f63..6f02147b6 100644
--- a/datapath-windows/ovsext/Util.h
+++ b/datapath-windows/ovsext/Util.h
@@ -152,4 +152,19 @@ UINT32 Rand()
     return seed.LowPart *= 0x8088405 + 1;
 }
 
+/*
+ *----------------------------------------------------------------------------
+ *  OvsGetMdlWithLowPriority --
+ *    Return the nonpaged system-space virtual address for the given MDL
+ *    `curMdl` using low page priority and no executable memory.
+ *----------------------------------------------------------------------------
+ */
+
+static __inline
+PVOID OvsGetMdlWithLowPriority(PMDL curMdl)
+{
+return	MmGetSystemAddressForMdlSafe(curMdl,
+                                     LowPagePriority | MdlMappingNoExecute);
+}
+
 #endif /* __UTIL_H_ */
diff --git a/datapath-windows/ovsext/Vxlan.c b/datapath-windows/ovsext/Vxlan.c
index 47c734e1e..09809d397 100644
--- a/datapath-windows/ovsext/Vxlan.c
+++ b/datapath-windows/ovsext/Vxlan.c
@@ -244,8 +244,7 @@ OvsDoEncapVxlan(POVS_VPORT_ENTRY vport,
         }
 
         curMdl = NET_BUFFER_CURRENT_MDL(curNb);
-        bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl,
-                                                           LowPagePriority);
+        bufferStart = (PUINT8)OvsGetMdlWithLowPriority(curMdl);
         if (!bufferStart) {
             status = NDIS_STATUS_RESOURCES;
             goto ret_error;
@@ -421,8 +420,8 @@ OvsDecapVxlan(POVS_SWITCH_CONTEXT switchContext,
     curNbl = *newNbl;
     curNb = NET_BUFFER_LIST_FIRST_NB(curNbl);
     curMdl = NET_BUFFER_CURRENT_MDL(curNb);
-    bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl, LowPagePriority) +
-                  NET_BUFFER_CURRENT_MDL_OFFSET(curNb);
+    bufferStart = (PUINT8)OvsGetMdlWithLowPriority(curMdl)
+        + NET_BUFFER_CURRENT_MDL_OFFSET(curNb);
     if (!bufferStart) {
         status = NDIS_STATUS_RESOURCES;
         goto dropNbl;