Re: [PATCH v12 for-xen-4.5 01/20] common/symbols: Export hypervisor symbols to privileged guest

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 09/26/2014 05:43 PM, Daniel De Graaf wrote:
>
>> @@ -601,6 +602,38 @@ ret_t 
>> do_platform_op(XEN_GUEST_HANDLE_PARAM(xen_platform_op_t) u_xenpf_op)
>>       }
>>       break;
>>
>> +    case XENPF_get_symbol:
>> +    {
>> +        static char name[KSYM_NAME_LEN + 1]; /* protected by 
>> xenpf_lock */
>> +        XEN_GUEST_HANDLE(char) nameh;
>> +        uint32_t namelen, copylen;
>> +
>> +        guest_from_compat_handle(nameh, op->u.symdata.name);
>> +
>> +        ret = xensyms_read(&op->u.symdata.symnum, &op->u.symdata.type,
>> +                           &op->u.symdata.address, name);
>> +
>> +        namelen = strlen(name) + 1;
>> +
>> +        if ( namelen > op->u.symdata.namelen )
>> +        {
>> +            /* Caller's buffer is too small for the whole string */
>> +            if ( op->u.symdata.namelen )
>> +                name[op->u.symdata.namelen] = '\0';
>
> I don't think this assignment is needed at all: name[copylen] is never
> copied to the guest and the buffer is not reused internally.


True, this is not needed.

Thanks.
-boris


>
>> +            copylen = op->u.symdata.namelen;
>> +        }
>> +        else
>> +            copylen = namelen;
>> +
>> +        op->u.symdata.namelen = namelen;
>> +
>> +        if ( !ret && copy_to_guest(nameh, name, copylen) )
>> +            ret = -EFAULT;
>> +        if ( !ret && __copy_field_to_guest(u_xenpf_op, op, u.symdata) )
>> +            ret = -EFAULT;
>> +    }
>> +    break;
>> +
>>       default:
>>           ret = -ENOSYS;
>>           break;
> [...]
>