NetworkPkg: Fix invalid pointer for DNS response token on error

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3719

This issue is introduced by the commit 43d7e607.
Token->RspData.H2AData is de-allocated on error but it is not
set to NULL. HTTP module attempts to free again and cause assert.

Signed-off-by: Baraneedharan Anbazhagan <anbazhagan@hp.com>
Reviewed-by: Wu Jiaxin <jiaxin.wu@intel.com>

NetworkPkg/DnsDxe/DnsImpl.c

diff --git a/NetworkPkg/DnsDxe/DnsImpl.c b/NetworkPkg/DnsDxe/DnsImpl.c
index 2edcb28..78a56f2 100644
--- a/NetworkPkg/DnsDxe/DnsImpl.c
+++ b/NetworkPkg/DnsDxe/DnsImpl.c
@@ -1700,6 +1700,7 @@
           }

 

           FreePool (Dns4TokenEntry->Token->RspData.H2AData);

+          Dns4TokenEntry->Token->RspData.H2AData = NULL;

         }

       }

     }

@@ -1731,6 +1732,7 @@
           }

 

           FreePool (Dns6TokenEntry->Token->RspData.H2AData);

+          Dns6TokenEntry->Token->RspData.H2AData = NULL;

         }

       }

     }