Re: [patch] NetworkPkg: Enhance the code in DNS driver.

[Laszlo Ersek <lersek@redhat.com>]

On 10/14/16 08:54, Zhang Lubo wrote:
> There may be an error happens when we use the
> configure function to set or change the configuration
> data for the DNS6 instance, So we will free the
> DnsServerList without configured to NULL. If we reset
> the instance with the parameter DnsConfigData to NULL, the
> DnsServerList will be freed twice.
> 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Zhang Lubo <lubo.zhang@intel.com>
> Cc: Ye Ting <ting.ye@intel.com>
> Cc: Fu Siyuan <siyuan.fu@intel.com>
> Cc: Wu Jiaxin <jiaxin.wu@intel.com>
> ---
>  NetworkPkg/DnsDxe/DnsProtocol.c | 4 ++++
>  1 file changed, 4 insertions(+)

The subject line of the patch is near useless, I'm afraid.

How about:

NetworkPkg/DnsDxe: eliminate double-free on DNS configuration failure

Thanks
Laszlo

> diff --git a/NetworkPkg/DnsDxe/DnsProtocol.c b/NetworkPkg/DnsDxe/DnsProtocol.c
> index 64fca6a..6d117b2 100644
> --- a/NetworkPkg/DnsDxe/DnsProtocol.c
> +++ b/NetworkPkg/DnsDxe/DnsProtocol.c
> @@ -285,10 +285,11 @@ Dns4Configure (
>      //
>      Status = Dns4ConfigUdp (Instance, Instance->UdpIo);
>      if (EFI_ERROR (Status)) {
>        if (Instance->Dns4CfgData.DnsServerList != NULL) {
>          FreePool (Instance->Dns4CfgData.DnsServerList);
> +        Instance->Dns4CfgData.DnsServerList = NULL;
>        }
>        goto ON_EXIT;
>      }
>  
>      //
> @@ -296,10 +297,11 @@ Dns4Configure (
>      //
>      Status = AddDns4ServerIp (&mDriverData->Dns4ServerList, Instance->SessionDnsServer.v4);
>      if (EFI_ERROR (Status)) {
>        if (Instance->Dns4CfgData.DnsServerList != NULL) {
>          FreePool (Instance->Dns4CfgData.DnsServerList);
> +        Instance->Dns4CfgData.DnsServerList = NULL;
>        }
>        goto ON_EXIT;
>      }
>      
>      Instance->State = DNS_STATE_CONFIGED;
> @@ -1106,10 +1108,11 @@ Dns6Configure (
>      //
>      Status = Dns6ConfigUdp (Instance, Instance->UdpIo);
>      if (EFI_ERROR (Status)) {
>        if (Instance->Dns6CfgData.DnsServerList != NULL) {
>          FreePool (Instance->Dns6CfgData.DnsServerList);
> +        Instance->Dns6CfgData.DnsServerList = NULL;
>        }
>        goto ON_EXIT;
>      }
>  
>      //
> @@ -1117,10 +1120,11 @@ Dns6Configure (
>      //
>      Status = AddDns6ServerIp (&mDriverData->Dns6ServerList, Instance->SessionDnsServer.v6);
>      if (EFI_ERROR (Status)) {
>        if (Instance->Dns6CfgData.DnsServerList != NULL) {
>          FreePool (Instance->Dns6CfgData.DnsServerList);
> +        Instance->Dns6CfgData.DnsServerList = NULL;
>        }
>        goto ON_EXIT;
>      }
>      
>      Instance->State = DNS_STATE_CONFIGED;
>