Re: [ros-diffs] [hpoussin] 18442: Don't always return STATUS_BUFFER_TOO_SMALL when an error occurs in ZwQueryValueKey.

[Alex Ionescu]

hpoussin(a)svn.reactos.com wrote:

>  Don't always return STATUS_BUFFER_TOO_SMALL when an
> error occurs in ZwQueryValueKey.
> The "if" was triggered because ValueInformation->DataLength is 0xcdcdcdcd at
> the return of the function
>  
But that means that the memory was freed during the failure, so now the 
ExFreePool will run into a double-free!

>  Modified: trunk/reactos/ntoskrnl/io/pnpmgr.c
>   
>
>  ------------------------------------------------------------------------
>  *Modified: trunk/reactos/ntoskrnl/io/pnpmgr.c*
>
> --- trunk/reactos/ntoskrnl/io/pnpmgr.c	2005-10-14 13:00:18 UTC (rev 18441)
> +++ trunk/reactos/ntoskrnl/io/pnpmgr.c	2005-10-14 13:04:11 UTC (rev 18442)
> @@ -322,15 +322,18 @@
>
>          *ResultLength = ValueInformation->DataLength;
>          ZwClose(KeyHandle);
>  
>   
>
> -        if (ValueInformation->DataLength > BufferLength)
> -          Status = STATUS_BUFFER_TOO_SMALL;
> -
>   
>
>          if (!NT_SUCCESS(Status))
>          {
>            ExFreePool(ValueInformation);
>            return Status;
>          }
>  
>   
>
> +        if (ValueInformation->DataLength > BufferLength)
> +        {
> +          ExFreePool(ValueInformation);
> +          return STATUS_BUFFER_TOO_SMALL;
> +        }
> +
>   
>
>          /* FIXME: Verify the value (NULL-terminated, correct format). */
>  
>          RtlCopyMemory(PropertyBuffer, ValueInformation->Data,
>   
>  
Please check this out in more detail...

Best regards,
Alex Ionescu