Re: [edk2-devel] [PATCH v1 1/1] NetworkPkg/Ip6Dxe: Validate source data record length

["Maciej Rabeda" <maciej.rabeda@linux.intel.com>]

Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com>

On 09-Apr-20 10:22, Siyuan, Fu wrote:
> Reviewed-by: Siyuan Fu <siyuan.fu@intel.com>
>
>> -----Original Message-----
>> From: michael.kubacki@outlook.com <michael.kubacki@outlook.com>
>> Sent: 2020年4月8日 13:47
>> To: devel@edk2.groups.io
>> Cc: Fu, Siyuan <siyuan.fu@intel.com>; Maciej Rabeda
>> <maciej.rabeda@linux.intel.com>; Wu, Jiaxin <jiaxin.wu@intel.com>
>> Subject: [PATCH v1 1/1] NetworkPkg/Ip6Dxe: Validate source data record
>> length
>>
>> From: Michael Kubacki <michael.kubacki@microsoft.com>
>>
>> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2273
>>
>> Ip6ConfigReadConfigData() reads configuration data from a UEFI variable
>> and copies the data to another buffer. This change checks that the length
>> of the data record being copied does not exceed the size of the source
>> UEFI variable data buffer.
>>
>> If the size is exceeded, this change follows existing logic to treat the
>> variable as corrupted and deletes the variable so it will be set again.
>>
>> Cc: Siyuan Fu <siyuan.fu@intel.com>
>> Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com>
>> Cc: Jiaxin Wu <jiaxin.wu@intel.com>
>> Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
>> ---
>>   NetworkPkg/Ip6Dxe/Ip6ConfigImpl.c | 47 +++++++++++++-------
>>   1 file changed, 30 insertions(+), 17 deletions(-)
>>
>> diff --git a/NetworkPkg/Ip6Dxe/Ip6ConfigImpl.c
>> b/NetworkPkg/Ip6Dxe/Ip6ConfigImpl.c
>> index eb2a80b64f15..ab3801336912 100644
>> --- a/NetworkPkg/Ip6Dxe/Ip6ConfigImpl.c
>> +++ b/NetworkPkg/Ip6Dxe/Ip6ConfigImpl.c
>> @@ -2,6 +2,7 @@
>>     The implementation of EFI IPv6 Configuration Protocol.
>>
>>     Copyright (c) 2009 - 2018, Intel Corporation. All rights reserved.<BR>
>> +  Copyright (c) Microsoft Corporation.<BR>
>>
>>     SPDX-License-Identifier: BSD-2-Clause-Patent
>>
>> @@ -390,24 +391,9 @@ Ip6ConfigReadConfigData (
>>                       );
>>       if (EFI_ERROR (Status) || (UINT16) (~NetblockChecksum ((UINT8 *)
>> Variable, (UINT32) VarSize)) != 0) {
>>         //
>> -      // GetVariable still error or the variable is corrupted.
>> -      // Fall back to the default value.
>> +      // GetVariable error or the variable is corrupted.
>>         //
>> -      FreePool (Variable);
>> -
>> -      //
>> -      // Remove the problematic variable and return EFI_NOT_FOUND, a new
>> -      // variable will be set again.
>> -      //
>> -      gRT->SetVariable (
>> -             VarName,
>> -             &gEfiIp6ConfigProtocolGuid,
>> -             IP6_CONFIG_VARIABLE_ATTRIBUTE,
>> -             0,
>> -             NULL
>> -             );
>> -
>> -      return EFI_NOT_FOUND;
>> +      goto Error;
>>       }
>>
>>       //
>> @@ -432,7 +418,12 @@ Ip6ConfigReadConfigData (
>>         if (!DATA_ATTRIB_SET (DataItem->Attribute, DATA_ATTRIB_SIZE_FIXED)) {
>>           //
>>           // This data item has variable length data.
>> +        // Check that the length is contained within the variable before
>> allocating.
>>           //
>> +        if (DataRecord.DataSize > VarSize - DataRecord.Offset) {
>> +          goto Error;
>> +        }
>> +
>>           DataItem->Data.Ptr = AllocatePool (DataRecord.DataSize);
>>           if (DataItem->Data.Ptr == NULL) {
>>             //
>> @@ -454,6 +445,28 @@ Ip6ConfigReadConfigData (
>>     }
>>
>>     return Status;
>> +
>> +Error:
>> +  //
>> +  // Fall back to the default value.
>> +  //
>> +  if (Variable != NULL) {
>> +    FreePool (Variable);
>> +  }
>> +
>> +  //
>> +  // Remove the problematic variable and return EFI_NOT_FOUND, a new
>> +  // variable will be set again.
>> +  //
>> +  gRT->SetVariable (
>> +         VarName,
>> +         &gEfiIp6ConfigProtocolGuid,
>> +         IP6_CONFIG_VARIABLE_ATTRIBUTE,
>> +         0,
>> +         NULL
>> +         );
>> +
>> +  return EFI_NOT_FOUND;
>>   }
>>
>>   /**
>> --
>> 2.16.3.windows.1
>
> 
>