[Patch] MdeModulePkg: Free NET_BUF data after it is sent out to avoid memory leak

[fanwang2 <fan.wang@intel.com>]

When build a DHCP message in function DhcpSendMessage() or DhcpRetransmit(),
a new NET_BUF is created by the library of NetbufFromExt, but it's not freed
after it is sent out. This patch is to fix this memory leak issue.

Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Wang Fan <fan.wang@intel.com>
---
 MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Io.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Io.c b/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Io.c
index 3898223..d90dc34 100644
--- a/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Io.c
+++ b/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Io.c
@@ -1397,23 +1397,22 @@ DhcpSendMessage (
     EndPoint.LocalAddr.Addr[0]  = DhcpSb->ClientAddr;
     UdpIo                       = DhcpSb->LeaseIoPort;
   }
 
   ASSERT (UdpIo != NULL);
-  NET_GET_REF (Wrap);
-  
+
   Status = UdpIoSendDatagram (
              UdpIo, 
              Wrap, 
              &EndPoint, 
              NULL, 
              DhcpOnPacketSent, 
              DhcpSb
              );
 
   if (EFI_ERROR (Status)) {
-    NET_PUT_REF (Wrap);
+    NetbufFree (Wrap);
     return EFI_ACCESS_DENIED;
   }
 
   return EFI_SUCCESS;
 }
@@ -1475,22 +1474,21 @@ DhcpRetransmit (
     UdpIo                       = DhcpSb->LeaseIoPort;
   }
 
   ASSERT (UdpIo != NULL);
 
-  NET_GET_REF (Wrap);
   Status = UdpIoSendDatagram (
              UdpIo,
              Wrap,
              &EndPoint,
              NULL,
              DhcpOnPacketSent,
              DhcpSb
              );
 
   if (EFI_ERROR (Status)) {
-    NET_PUT_REF (Wrap);
+    NetbufFree (Wrap);
     return EFI_ACCESS_DENIED;
   }
 
   return EFI_SUCCESS;
 }
-- 
1.9.5.msysgit.1